DA 592 - Term Project Report - Berker Kozan Can Koklu

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Sabancı University Data Analytics M.Sc. Programme DA 592 - 2015-2016 Term Project Grupo Bimbo Inventory Demand - Kaggle Contest Students: Berker Kozan, Can Köklü

Transcript of DA 592 - Term Project Report - Berker Kozan Can Koklu

Page 1: DA 592 - Term Project Report - Berker Kozan Can Koklu

 

 

 

 

 

Sabancı University Data Analytics M.Sc. Programme 

 

DA 592 - 2015-2016 Term Project 

 

Grupo Bimbo Inventory Demand - Kaggle Contest 

 

 

 

Students: Berker Kozan, Can Köklü 

   

 

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Abstract 

This data analytics project was done for a Kaggle contest where the goal was to perform 

demand prediction for Grupo Bimbo company. Python language was used with Jupyter 

notebooks. XGBoost library was used to perform training and predictions. 

Various feature engineering features such as NLTK for text extraction, creation of lag 

columns and averaging over a large number of variables were used to enhance data. 

After the train table was created, XGBoost was utilized to optimize according to the 

scoring function dictated by the contest, RMSLE. Hyperparameter tuning was also 

leveraged after feature selection based on feature importance and correlation analysis 

to determine the best parameters for the XGBoost optimizer. 

The final submission to Kaggle achieved a score of 0.48666; placing our team in the top 

17% of the 2000 contestants. 

The biggest challenges were related to analyzing and training on a large data set. This 

was overcome by forcing the data types to smaller types (unsigned integers, low 

accuracy floats, etc.), using HDF5 file format for data storage and launching a 

powerful Google Cloud Compute Preemptible Instance (with 208 GB RAM). 

Further improvements would include attempting hyperparameter tuning across a wider 

range of training tables (with different features) and also implementing a failsafe 

method for running the experiment in preemptible instances. Additionally, creating 

different models and averaging them to find optimal and non-overfitted models would 

have yielded better results. 

 

 

Keywords: data science, kaggle, demand prediction, python, jupyter, xgboost, cloud, google cloud compute, hdf5, hyperparameter tuning, feature selection 

 

   

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Table of Contents 

 

Abstract 1 

Table of Contents 2 

Introduction 3 

What is Kaggle? 3 

What is the contest about? 3 

Why this project? 4 

Tools Used 4 

Python 4 

Platforms 5 

Data Exploration 6 

Definition of the Data Sets 6 

Exploratory Data Analysis 7 

Data Types and Sizes 7 

Distributions and Summary of Data

Correlations 9 

Decreasing the Data Size 9 

Models 10 

Naive Prediction 10 

Score 10 

NLTK based Modelling 10 

Feature Engineering 10 

Modeling 11 

Technical Problems 11 

Garbage Collection 11 

Data Size 11 

Score 12 

Conclusion 12 

Final Models 12 

Digging Deeper in Data 

Exploration 12 

Demanda - Dev - Venta 

Relationship 12 

Train - Test Difference 13 

Feature Engineering 14 

Agencia 14 

Producto 14 

Client Features 14 

Demand Features 15 

General Totals 15 

Validation Technique 17 

Xgboost 17 

Training 18 

Hyperparameter Tuning 18 

Max Depth: 18 

Subsample: 18 

ColSample By Tree: 18 

Learning Rate: 19 

Technical Problems 19 

Storing Data 19 

RAM Problem 19 

Code Reuse and Automatization 19 

Results 20 

Conclusion 21 

Critical Mistakes 22 

Poor data exploration 22 

Not preparing for system outages

22 

Performing hyperparameter tuning 

too late 22 

Further Exploration 22 

Partial Fitting 22 

Multiple Models 22 

Neural Networks 22 

 

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Introduction 

What is Kaggle? 

Kaggle is a website founded in 2010 that provides data science challenges to its 1

participants. Participants compete against each other to solve data science problems. 

Kaggle has unranked “practice” challenges as well as contests with monetary rewards. 

Companies that have data challenges work together with Kaggle to formulate the problem 

and reward the top performers. 

What is the contest about? 

The contest that we have taken on for our project belongs to a Mexican company named 2

Grupo Bimbo. Grupo Bimbo is a company that produces and distributes fresh bakery 

products. The nature of the problem at its core is demand estimation. 

Grupo Bimbo produces the products and ships them from storage facilities (agencies) to 

stores (clients). The following week, a certain number of products that aren’t sold are 

returned from the clients to Bimbo. To maximize their profits, Grupo Bimbo needs to 

predict the demand of stores accurately to minimize these returns. 

In the contest, we are provided with 9 weeks worth of data regarding these shipments 

and we are asked to predict the demand for weeks 10 and 11. Participants are allowed to 

submit 3 sets of predictions every day until the deadline of the project and can pick 

any two of these predictions as their final submissions. 

As a standard practice at Kaggle, when making initial submissions, the predictions are 

ranked based on a “public” ranking which only evaluates a certain part of the 

submission. This is done to prevent gaming the system by overfitting through trial & 

error of submissions. For this contest, the “public” ranking is done on week 10 data; 

meaning, when submitting our predictions we would only be able to see our performance 

for week 10. The private performance of our predictions (i.e. weeks 11) are only shown 

after the contest ends. 

For this contest the evaluation metric is the Root Mean Squared Logarithmic Error of 

our predictions. 

1 "About | Kaggle." 2012. 10 Sep. 2016 < https://www.kaggle.com/about > 2 "Grupo Bimbo Inventory Demand | Kaggle." 2016. 10 Sep. 2016 < https://www.kaggle.com/c/grupo-bimbo-inventory-demand > 

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Why this project? 

We decided to do a Kaggle contest for our project for various reasons: 

1. It would allow us to benchmark our data science abilities in an international 

field. 

2. Kaggle has very active forums for each individual contest and these would provide 

us with great new methods and insights in solving problems. 

3. Since the data provided is clean, we could spend more time in feature and model 

building rather than data cleaning. 

4. We could work towards a clear goal and not be distracted. 

5. From the number of contest in Kaggle, we picked the Grupo Bimbo project because: 

a. It deals with text data which is considerably easier to work with for 

beginners. 

b. The data was very large and provided a learning opportunity in working 

with large data sets. 

c. The deadline of the project (August 30) was in line with the deadline of 

our term project. 

Tools Used 

Python 

We decided to use Python (version 2.7 ) as the our scripting language. This is the 3

language we worked with most in our programme and also one of the most popular data 

science languages. We built our systems on the Anaconda package by Continuum as it 4

offers a large number of libraries that help us face the challenges. 

We mainly ran Jupyter (IPython) notebooks on various systems to code and report 5

results. 

A few of the specific tools/packages that we used were: 

3 "Python 2.7.0 Release | Python.org." 2014. 10 Sep. 2016 < https://www.python.org/download/releases/2.7/ > 4 "Download Anaconda Now! | Continuum - Continuum Analytics." 2015. 10 Sep. 2016 < https://www.continuum.io/downloads > 5 "Project Jupyter | Home." 2014. 10 Sep. 2016 < http://jupyter.org/ > 

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● NLTK : NLTK is the most popular Natural Language Processing Toolkit for Python. 6

It offers great features like stemming, tokenizing and chunking in multiple 

languages. This was critical since the product names were in Spanish. 

● XGBoost: XGBoost is a library that can be used in conjunction with various 

scripting languages (including R and Python) that is designed for gradient 

boosting trees. It is much faster than regular scripting tools since the 

computational parts are written and precompiled in C++. We picked this solution 

based simply on its fame, as many of the winners have used this tool in Kaggle 

contests . 7

● Pickle : The pickle module implements binary protocols for serializing and 8

de-serializing a Python object structure. 

● HDF5 File Format: HDF is self-describing, allowing an application to interpret 9

the structure and contents of a file with no outside information, a 

general-purpose, machine-independent standard for storing scientific data in 

files, developed by the National Center for Supercomputing Applications (NCSA). 

● Scikit-Learn : Scikit-Learn is a simple and efficient tool for data mining and 10

machine learning beside that it’s free and build on numpy, matplotlib and scipy. 

We used it on feature extraction phase. 

● NumPy : NumPy is an open source extension module for Python, which provides fast 11

precompiled functions for mathematical and numerical routines. Furthermore, NumPy 

enriches the programming language Python with powerful data structures for 

efficient computation of multidimensional arrays and matrices. 

● SciPy : SciPy is a Python-based ecosystem of open-source software for 12

mathematics, science, and engineering. We used it for sparse matrices. 

● Garbage Collector : The gc module was used in order to free up memory 13

periodically to optimize performance. 

Platforms 

For coding and performing our computations, we initially attempted to use our laptops 

(a Macbook Pro and an Ubuntu Machine each with 16GB of RAM). However, after getting 

numerous Memory Errors, we gradually came to realize that our computers would not be 

able to run the computations that we need (at least not in an efficient and timely 

manner). To solve our problem we turned to cloud services. 

We first set up an EC2 instance on Amazon Web Services with about 100GB of RAM and 16 

virtual CPU cores, using a public tutorial . However, running such a powerful instance 14

6 "Natural Language Toolkit — NLTK 3.0 documentation." 2005. 10 Sep. 2016 < http://www.nltk.org/ > 7 "xgboost/demo at master · dmlc/xgboost · GitHub." 2015. 10 Sep. 2016 < https://github.com/dmlc/xgboost/tree/master/demo > 8 "12.1. pickle — Python object serialization — Python 3.5.2 documentation." 2014. 20 Sep. 2016 < https://docs.python.org/3/library/pickle.html > 9 "Importing HDF5 Files - MATLAB & Simulink - MathWorks." 2012. 20 Sep. 2016 < http://www.mathworks.com/help/matlab/import_export/importing-hierarchical-data-format-hdf5-files.html > 10 "scikit-learn: machine learning in Python — scikit-learn 0.17.1 ..." 2011. 20 Sep. 2016 < http://scikit-learn.org/ > 11 "What is NumPy? - Numpy and Scipy Documentation." 2009. 20 Sep. 2016 < http://docs.scipy.org/doc/numpy/user/whatisnumpy.html > 12 "SciPy.org — SciPy.org." 2002. 21 Sep. 2016 < http://www.scipy.org/ > 13 "28.12. gc — Garbage Collector interface — Python 2.7.12 ..." 2014. 21 Sep. 2016 < https://docs.python.org/2/library/gc.html > 14 "Setting up AWS for Kaggle Part 1 – Creating a first Instance – grants ..." 2016. 10 Sep. 2016 < http://www.grant-mckinnon.com/?p=6 > 

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continuously proved costly; a two day attempt to build and run models cost over 150USD. 

(An important side note, one should make sure that all items that relate to the 

instance created are removed completely to avoid incurring charges. In the case of one 

of the authors of this paper, an extra 50USD was later charged because backup copies of 

the instances were not deleted.) 

We then decided to switch to Google Cloud Compute service; building a system with 

similar specs, again following a publicly available tutorial . Although slightly 15

cheaper, having a dedicated machine run for an entire day again proved costly, 

incurring about 50USD. At this point we decided to find a cheaper solution and decided 

to look at Amazon’s Spot Instances and Google’s Preemptible Instances. 

Both Amazon Spot Instances and Google Preemptible Instances operate on the principle 

that they offer the company's surplus computing power at a discount. The caveat being 

that if there are other consumers that want to use this computing power, the instances 

can be stopped by the company at any point. The biggest difference between the two is 

that Amazon offers a more bidding model where the prices for the computing power 

fluctuates; if the bid that the buyer is higher than the current market price, the 

instance remains active; however if the market price raises above the bid, it is shut 

down. Google on the other hand offers a specific price for the instance . 16

We eventually settled down on using a Google Preemptible instance with 32 virtual CPUs 

and 208 GB of RAM. We had to deal with a premature shutdown only once while running the 

instance over the course of three days. The total cost of the preemptible instances and 

backups etc came to about 60 USD. 

The key interface to the Google Cloud interface was a command prompt terminal, where 

the Jupyter notebook was initiated and data files were uploaded and submission files 

were downloaded via SSH. 

Github  17

GitHub is a code hosting platform for version control and collaboration which lets 

people work together on projects from anywhere. We used this to work on our codes in 

parallel while easily merging our developments. 

Data Exploration 

Definition of the Data Sets 

The data sets that we were provided with was as follows: 

● train.csv — the training set, total Demand data from clients and products per 

week for weeks 3-9; containing the following fields: 

○ Semana - The week 

○ Agencia_ID - ID of the storage facility from which the order is 

dispatched. 

○ Canal_ID - The channel through which the order is placed. 

15 "Set up Anaconda + IPython + Tensorflow + Julia on a Google ..." 2016. 10 Sep. 2016 < https://haroldsoh.com/2016/04/28/set-up-anaconda-ipython-tensorflow-julia-on-a-google-compute-engine-vm/ > 16 "What are the key differences between AWS Spot Instances ... - Quora." 2015. 10 Sep. 2016 < https://www.quora.com/What-are-the-key-differences-between-AWS-Spot-Instances-and-Googles-Preemptive-Instances > 17 "Hello World · GitHub Guides." 2014. 20 Sep. 2016 < https://guides.github.com/activities/hello-world/ > 

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○ Ruta_SAK - The route ID of the delivery route. 

○ Cliente_ID - The Client ID 

○ Producto_ID - The Product ID 

○ Venta_uni_hoy - The number of items that were ordered 

○ Venta_hoy - The total cost of the items that were ordered 

○ Dev_uni_proxima - The number of items that were returned. 

○ Dev_proxima - The total cost of the items that were returned. 

○ Demanda_uni_equil - Actual demand (the stock that was actually sold), this is the label that we need to predict for weeks 10 and 11. 

● test.csv — the test set, data from clients and products for weeks 10 and 11 

containing the fields: 

○ Id  

○ Semana 

○ Agencia_ID 

○ Canal_ID 

○ Ruta_SAK 

○ Cliente_ID 

○ Producto_ID 

● cliente_tabla.csv — client names (can be joined with train/test on Cliente_ID) 

● producto_tabla.csv — product names (can be joined with train/test on 

Producto_ID) 

● town_state.csv — town and state (can be joined with train/test on Agencia_ID) 

● sample_submission.csv — a sample submission file in the correct format 

 

Image 1: Data Structure 

None of the numeric variables existing in train data are in the test set of the data, 

so the problem here is predicting the demand with only 6 categorical features. 

Exploratory Data Analysis 

Data Types and Sizes 

The sizes of the data files were as follows: 

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● town_state.csv 0.03MB 

● train.csv 3199.36MB 

● cliente_tabla.csv 21.25MB 

● test.csv 251.11MB 

● producto_tabla.csv 0.11MB 

● sample_submission.csv 68.88MB 

Distributions and Summary of Data 

 

Image 2: Summary of Train Data 

 

Image 3: Summary of Train Data (cont.) 

 

Image 4: Distribution of Target Variable 

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Target variable's mean is 7, median is 3, max is 5000, std is 25 and %75 of the data is 

between 0-6. This is a classical right-skewed data and this explains why evaluation 

metric is RMSLE. Moreover, we logged target variable (log(variable+1)) before starting 

modeling and than take exponential of it before submitting (exp(variable)-1). 

Correlations 

 

Image 5: Scatter Plots of Key Variables 

In these scatter plots, we see that orders are highly correlated with demand, and 

secondly, where demand is high returns are low. 

Decreasing the Data Size 

In order to optimize RAM usage and speed up XGBoost’s performance, we made sure to 

force the type of the data fields explicitly. We defined all our integers to use 

unsigned integer format and decreased the accuracy of floating point integers as much 

as possible. For example, Canal_ID can be uint8. After conversions, memory is reduced 

to 2.1 gb from 6.1gb. 

 

Data with Default Data Types  Data with Optimized Data Types 

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RangeIndex: 74180464 entries, 0 to 74180463 

Data columns (total 11 columns): 

Semana int64 

Agencia_ID int64 

Canal_ID int64 

Ruta_SAK int64 

Cliente_ID int64 

Producto_ID int64 

Venta_uni_hoy int64 

Venta_hoy float64 

Dev_uni_proxima int64 

Dev_proxima float64 

Demanda_uni_equil int64 

dtypes: float64(2), int64(9) 

 

memory usage: 6.1 GB 

RangeIndex: 74180464 entries, 0 to 74180463 

Data columns (total 11 columns): 

Semana uint8 

Agencia_ID uint16 

Canal_ID uint8 

Ruta_SAK uint16 

Cliente_ID uint32 

Producto_ID uint16 

Venta_uni_hoy uint16 

Venta_hoy float32 

Dev_uni_proxima uint32 

Dev_proxima float32 

Demanda_uni_equil uint32 

dtypes: float32(2), uint16(4), uint32(3), 

uint8(2) 

memory usage: 2.1 GB 

 

Models 

Naive Prediction 

We first decided to create a naive prediction; for this we grouped the training data 

based on Product ID, Client ID, Agency ID and Route ID. We simply took the median of 

this grouping, if this specific grouping did not exist, in the training data set, we 

defaulted back to the product’s median demand and if this also did not exist, we simply 

took the average of the overall demand. 

Score 

This method resulted in a score of 0.73 when submitted. 

 

NLTK based Modelling 

Feature Engineering 

We utilized the NLTK library to extract the following information from the Producto 

Tabla file (we used a slightly modified version of a code provided by Andrey Vykhodtsev

) 18

● Weight: In grams 

● Pieces 

● Brand Name: Extracted through a three letter acronym 

● Short Name: Extracted from the Product Name field. We processed this information 

using the NLTK library. We first removed the Spanish “stop words” and then used 

the stemming in order to make sure only the cores of the names remained. 

18 "Exploring products - Kaggle." 2016. 10 Sep. 2016 < https://www.kaggle.com/vykhand/grupo-bimbo-inventory-demand/exploring-products > 

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Image 6: Product Data Names after preprocessing 

Modeling 

We wanted to model text data and predict. Here are the steps that were taken: 

1) Separate x and y of train data 

2) Append test data to train data to align them to have same sparse product features 

order (If they don’t have same column order, training gives false results). 

3) Merge this data with products. 

4) Use “count vectorizer” of Scikit-learn on brand and short_name columns to create 

sparse count-word matrices and append them to train-test data horizontally. 

5) Separate appended train and test data. 

6) Train Xgboost with default parameters on train data and predict test data. 

Technical Problems 

1) Garbage Collection 

Garbage collection was a big problem because of the size of the data. When we 

stopped using a python object, we had to remove and force garbage collection 

mechanism to free this memory. For this the the gc library was used. 19

2) Data Size 

Before using xgboost, we had 70+ million records with 577 columns. Holding this 

sparse data in memory with dataframe was impossible. We solved this issue with 

sparse matrices of SciPy library.  

In the example below, instead of holding all data including zeros in memory, 

sparse method holds only data different than 0. There are many sparse matrices 

methods. We used “CSR” and “COO” ones . 20

19 "28.12. gc — Garbage Collector interface — Python 2.7.12 ..." 2014. 21 Sep. 2016 < https://docs.python.org/2/library/gc.html > 20 "Sparse matrices (scipy.sparse) — SciPy v0.18.1 Reference Guide." 2008. 21 Sep. 2016 < http://docs.scipy.org/doc/scipy/reference/sparse.html > 

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Image 7: Visual explanation of how the COO sparse matrix works. 

Score 

The RMSLE scores obtained by using this method were as follows: 

Validation  Test 10  Test 11 (Private) 

0.764  0.775  0.781 

Conclusion 

These scores are worse than the naive approach, so we started to think about a new 

model. 

Final Models 

Digging Deeper in Data Exploration 

1. Demanda - Dev - Venta Relationship 

On data description page of contest, it’s said that Demanda = Venta-Dev except 

some return situations. 

When we query this equation, there are 615000 records which are exceptions as 

shown below. It can mean that returns can be done after more than 1 week. We 

flagged these products.  

 

Image 8: Exceptional cases where the number of returns is higher than the number 

of orders (lagging returns). 

Secondly, we query Demanda = 0 & Dev = 0 and there are 199767 records which 

includes only returns. When we find demand mean of a product, these records can 

falsify our results as they only include return values. 

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Image 9: Exceptional cases where the number of orders and demand are both zero. 

2. Train - Test Difference 

We analyzed the missing products, clients, agencies, routes and product-client 

tuples which exist in train but not in test and vice versa or in specific files 

Producto     

Train - Producto File  Test - Producto File  Test - Train 

0  0  34 

This table means; 

● There are no products existing in train but not in producto file 

● There are no products existing in test but not in producto file 

● There are 34 products existing in test but not in train (probably new 

products) 

Similarly, the other missing items are listed below: 

Cliente     

Train - Cliente File  Test - Cliente File  Test - Train 

0  0  9663 

 

Agencia     

Train - Agencia File  Test - Agencia File  Test - Train 

0  0  0 

 

Route   

Train - Test  Test - Train 

17  1012 

 

Producto Client Tuple 

Test - Train 

1280296 

The important outcome of this analysis was that: we should build a general model that can handle new products, clients and routes which don’t exist in train data but in test data. 

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Feature Engineering 

In order to provide our models with more information, we had to perform some feature 

engineering. 

Agencia 

Agencia file shows each agency’s town id and state name. We can merge this file with 

train and test data on Agencia_ID column and encode state columns into integers. 

 

Image 10: Agencia Table after processing. 

Producto 

We used features from NLTK model, weights and pieces. In addition to them, we included 

short names of product and brand id.  

In the picture below, we can see same product with different weights and different ids. 

We take the short name of this products (we will add a feature like they are the same 

product) and include them to the features. Later we will see why. 

Product file 

2025 , Pan Blanco 460g BIM 2025 

2027 , Pan Blanco 567g WON 2027 

Client Features 

The Client Features were more difficult to engineer. Unlike the product table, the 

client table had a large number of duplicates, where clients names were misspelled in 

different cases. We removed the duplicates from the client table and then used a code 

snippet provided by AbderRahman Sobh (the process made use of using TF-IDF scoring of 21

the client names and then manual selection of certain keywords) in order to classify 

the clients based on their types, resulting in the following categorization: 

● Individual 353145 

● NO IDENTIFICADO 281670 

● Small Franchise 160501 

● General Market/Mart 66416 

● Eatery 30419 

● Supermarket 16019 

● Oxxo Store 9313 

● Hospital/Pharmacy 5798 

21 "Classifying Client Type using Client Names - Kaggle." 2016. 10 Sep. 2016 < https://www.kaggle.com/abbysobh/grupo-bimbo-inventory-demand/classifying-client-type-using-client-names > 

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● School 5705 

● Post 2667 

● Hotel 1127 

● Fresh Market 1069 

● Govt Store 959 

● Bimbo Store 320 

● Walmart 220 

● Consignment 14 

Demand Features 

This was the most critical part of our data structure. We generated 4 new columns for 

our training and testing data and named them Lag0, Lag1, Lag2 and Lag3. We asked 

ourselves why we hadn’t added the product’s ex demands.  

Lag0 is a special case that attempts to find the average demand for a specific row. 

This is done by attempting to find the average based on a large number of variables (as 

specific as possible) and failing that, attempting to find the average of a fewer 

number of variables (a more relaxed, less accurate and more general average). 

For example, 

● Average demand based on: 

"Producto_ID", "Cliente_ID", "Ruta_SAK", "Agencia_ID", "Canal_ID" 

● If this combination is not found, attempt to find average based on: 

"Producto_ID", "Cliente_ID", "Ruta_SAK", "Agencia_ID" 

● If this combination is not found, attempt to find average based on: 

"Producto_ID", "Cliente_ID", "Ruta_SAK" 

● And so on and so forth. 

This was done in the order of finding various averages based on product id first, then 

falling back on averages based on the short names of products , failing that, falling back on averages based on the brand names . 

Lag 1 through 3 were constructed in a similar fashion but were more strict and 

considered only a single week’s data. In these cases, we did not want to create any 

information based on Brand names as it would be too general. Only combinations with 

product id and product short name were used. So for a line of training data that 

pertained to week 7, Lag 1 would be the averages of that product id or product name 

based on week 6 data; Lag 2 would be averages of week 5 data; and so on and so forth. 

General Totals 

After obtaining the above averages, we also included the following: 

● Total Venta per client (giro of client) 

● Total Venta_uni_hoy per client (total unit product sold by a client) 

● Division of sum of venta_hoy to venta_uni_hoy (giving the approximate price per 

unit). 

● Division of sum of demand to sum of Venta uni (giving the ratio of goods actually 

sold by the client, i.e. ability to sell inventory) 

This was done for product short names and also product ids; resulting in an additional 

12 more columns for our training data. Other added columns are shown below: 

● Client per town 

● Sum of returns of product 

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● Sum of returns of short name of a product 

After eliminating highly correlated features (%90), the training data table was as 

follows: 

Int64Index: 74180464 entries, 0 to 74180463 Data columns (total 36 columns): Semana uint8 Agencia_ID uint16 Canal_ID uint8 Ruta_SAK uint16 Cliente_ID uint32 Producto_ID uint16 Venta_uni_hoy uint16 Venta_hoy �oat32 Dev_uni_proxima uint32 Dev_proxima �oat32 Demanda_uni_equil �oat64 Town_ID uint16 State_ID uint8 weight uint16 pieces uint8 Prod_name_ID uint16 Brand_ID uint8 Demanda_uni_equil_original �oat64 DemandaNotEqualTheDifferenceOfVentaUniAndDev bool Lag0 �oat64 Lag1 �oat64 Lag2 �oat64 Lag3 �oat64 weightppieces uint16 Client_Sum_Venta_hoy �oat32 Client_Sum_Venta_uni_hoy �oat32 Client_Sum_venta_div_venta_uni �oat32 prod_name_sum_Venta_hoy �oat32 prod_name_sum_Venta_uni_hoy �oat32 prod_name_sum_venta_div_venta_uni �oat32 Producto_sum_Venta_hoy �oat32 Producto_sum_Venta_uni_hoy �oat32 Producto_sum_venta_div_venta_uni �oat32 Producto_ID_sum_demanda_divide_sum_venta_uni �oat64 Prod_name_ID_sum_demanda_divide_sum_venta_uni �oat64 Cliente_ID_sum_demanda_divide_sum_venta_uni �oat64 memory usage: 10.6 GB 

 

   

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Validation Technique 

Validation is the maybe the most critical part of a data science project. Top priority 

was to not overfitting the data. We used different models to predict week 10 and week 

11. 

 

Image 11: Structure of training, validation and test mechanism. 

We used 6th and 7th week data as training. Our validation for week 10 was 8th, our 

validation for week 11 was 9th. In the latter one, we didn’t use Lag1 variable, because 

it means that in order to predict week 11, we should use week 10’s demand (Lag1 of week 

11 is week 10) which doesn’t exist. Or, we should predict week 10 first and with this 

predicted demands, we predict week 11 but it carries error from week 10 to week 11. 

After feature extraction phase and adding features to each record, we deleted first 3 

weeks. Because they don’t have Lag1, Lag2 and Lag3 features. 

Xgboost 

Xgboost can be given 2 different datasets (train and validation). With playing with 

parameters, we can make it train until the validation score stops increasing after “N” 

iterations. It automatically stops and tells you the best iteration number and its 

score. 

Xgboost can also give feature importances according to the counts of features on trees 

of model. For example: 

 

Image 12: Feature importance graph of fitted training data based on XGboost 

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Training 

We started to make models after defining validation strategy and feature extraction. 

Features  Validation 1 (Week 8) 

Validation 2 (Week 9) 

Trial 1  0.476226  0.498475 

Trial 2: Removing highly correlated features  0.477067  0.493038 

Trial 3: Adding lag interactions.  0.502514  N/A 

Trial 4: Adding more lag interactions  0.51825  N/A 

Trial 5: Lag interactions but removing more 

correlated features 

0.517606  N/A 

Trial 6: Replacing extreme values with NAN  0.517467  0.517375 

Trial 7: Removing low importance features (all 

lag interactions are removed) 

0.480394  0.494104 

Trial 8: Adding Client Types  0.48101  0.494804 

Many other variations were tried but abandoned due to poor performance. 

Interestingly, the original data set (with engineered features such as averages, lags 

etc.) resulted in the best performance. There is a caveat however, these attempts were 

all made with a fixed setting in XGBoost, as will be seen next, the number of trees may 

have been set too low in these trials to take into account the benefits of added 

features such as interactions between lags or clients types etc. 

Hyperparameter Tuning 

After selecting the data set, we proceeded with hyperparameter tuning of the XGBoost 

model. 

The XGBoost library has numerous parameters, the ones that were used for tuning were: 

Max Depth: 

The maximum depth of the decision trees. 

● Values tried: 10, 12, 8, 6, 14, 18, 20, 22 

● Optimal Value: 22 

Subsample: 

The subsampling rate of rows of the data. 

● Values tried: 1, 0.9, 0.8, 0.6 

● Optimal Value: 0.9 

ColSample By Tree: 

The subsampling rate of columns of the data. 

● Values tried: 0.4, 0.3, 0.5, 0.6, 0.8, 1 

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● Optimal Value: 0.4 

Learning Rate: 

The gradient descent optimization parameter (the size of each step). 

● Values tried: 0.1, 0.05 

● Optimal Value: 0.05 

Features  Validation 1 (Week 8) 

Validation 2 (Week 9) 

Original Training  0.476226  0.498475 

Training after Parameter Tuning  0.469628  0.489799 

Technical Problems 

Storing Data 

“CSV” file type is very slow to load and save. In addition to that, it isn’t 

self-describing. When we try to load data from it, we have to do all conversions as we 

did before saving it. We searched for a better file format to store that much data. 

Firstly, we tried “pickle” library which we used for storing xgboost models because of 

self-describing feature. But after file size gets bigger, it starts to give error. 

Secondly, we tried “HDF5” which is designed for storing big data on file. It was both 

very fast to load and save and also self-describing. We picked this one. 

RAM Problem 

Due to the size of the training and test tables, it was not possible to perform the 

operations using our underpowered laptops. Attempting to join large tables or use 

XGBoost to create models always resulted in memory errors. We solved this issue by 

migrating our environment to Google Cloud Compute. We used linux command line prompts 

to install Anaconda and related libraries and then launched Jupyter notebook to create 

a development environment. At its highest level, our instance (with 32 virtual CPUs and 

208GB RAM) was performing at 100% CPU load and 40% RAM usage. Training and predicting 

over our full train and test data took more than 2 hours. 

Code Reuse and Automatization 

There were lots of coding challenges for us as follows: 

● Opening csv files with predefined data types and names 

● Handling hdf5 files 

● Adding configurable features (Lag0, Lag1, …) to data 

● Automatically deleting first “N” lagged weeks from train data 

● Appending test to train data 

● Separating test and train data automatically  

● Xgboost configurable hyperparameter tuning 

● Handling memory issues 

We solved this issues with Object Oriented Programming with Python. This is the 

structure of our general class. class FeatureEngineering : 

def __init__ ( self , ValidationStart, ValidationEnd, trainHdfPath, trainHdfFile, 

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testHdfPath1, testHdfPath2, testHdfFile, testTypes, trainTypes, trainCsvPath, testCsvPath, 

maxLag =0 ) 

def __printDataFrameBasics__ (data)   

def ReadHdf ( self , trainOrTestOrBoth) 

def ReadCsv ( self , trainOrTestOrBoth) 

def ConvertCsvToHdf (csvPath, HdfPath, HdfName, ColumnTypeDict) 

def Preprocess ( self , trainOrTestOrBoth, columnFunctionTypeList)   

def SaveDataFrameToHdf ( self ,trainOrTestOrBoth) 

def AddCon�gurableFeaturesToTrain ( self , con�g) 

def DeleteLaggedWeeksFromTrain ( self ) 

def ReadFirstNRowsOfACsv ( self , nrows, trainOrTestOrBoth) 

def AppendTestToTrain ( self ,deleteTest = True ) 

def SplitTrainToTestUsingValidationStart ( self ) 

We can use this class by giving configurable parameters. parameterDict = { "ValidationStart" : 8 , "ValidationEnd" : 9 , "maxLag" : 3 , 

"trainHdfPath" : '../../input/train_wz.h5' , "trainHdfFile" : "train" , 

"testHdfPath1" : "../../input/test1_wz.h5" , "testHdfPath2" : "../../input/test2_wz.h5" , 

"testHdfFile" : "test" ,  

"trainTypes" : { 'Semana' :np . uint8, 'Demanda_uni_equil' : np . uint32}, "testTypes" : 

{ 'id' :np . uint32, 'Semana' :np . uint8, 'Agencia_ID' :np . uint16}, 

"trainCsvPath" : '../../input/train.csv' , "testCsvPath" : '../../input/test.csv' } 

FE = FeatureEngineering( ** parameterDict) 

To add complex lagged feature, we build an automation system which works with a config 

variable. con�gLag0Target1DeleteColumnsFalse = Con�gElements( 0 ,[ ( "SPClRACh0_mean" , 

[ "Producto_ID, "Cliente_ID, "Ruta_SAK, "Agencia_ID, "Canal_ID], [ "mean" ]), 

( "SPClRA0_mean" ,  

[ "Producto_ID" , "Cliente_ID" , "Ruta_SAK" , "Agencia_ID" ], [ "mean" ]), 

( "SB0_mean" ,[ "Brand_ID" ], [ "mean" ])], "Lag0" , True ) 

FE . AddCon�gurableFeaturesToTrain(con�gLag0Target1) 

To do hyperparameter tuning automatically, we wrote a python function. defaultParams = { "max_depth" : 10 , "subsample" : 1. , "colsample_bytree" : 0.4 , "missing" :np . nan, 

"n_estimators" : 500 , "learning_rate" : 0.1 } 

testParams = [( "max_depth" ,[ 12 , 8 , 6 , 14,16,18,20,22 ]), ( "subsample" ,[ 0.9 , 0.8 , 0.6 ]), 

( "colsample_bytree" ,[ 0.3 , 0.5 , 0.6 , 0.8 , 1 ]), ( "learning_rate" ,[ 0.05 ])] 

�tParams = { "verbose" : 2 , "early_stopping_rounds" : 10 } 

GiveBestParameterWithoutCV(defaultParams, testParams, X_train, X_test, y_train, y_test, 

�tParams ) 

 

   

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Results 

Over the course of the contest, we can name 4 mile stone submissions. The validation 

and public and private scores of these submissions are shown below. 

Model  Validation 1  Validation 2  Public Score  Private Score 

Naive 

(averages) 

0.736    0.734  0.754 

Optimized with 

Product Data 

via NLTK 

0.764    0.775  0.781 

XGBoost with 

default 

parameters 

0.476226  0.498475  0.46949  0.49596 

XGBoost with 

parameter 

tuning 

0.469628  0.489799  0.46257  0.48666 

We can see from the results that we didn’t overfit data at any point. 

For our final submission of predictions; we achieved a score of 0.48666; placing our 

team in the top 17% of the 2000 contestants. 

 

 

Looking over the scores of other participants, we’d like to say that for first time 

participants of a Kaggle contest, our results were very promising. 

Conclusion 

We are extremely happy that we picked a Kaggle contest for our project. It allowed us 

to work on a common real world problem while giving us a benchmark of our abilities in 

the global arena. 

We learned to leverage powerful cloud computing capabilities across various platforms 

while also learning how to manipulate large data sets with memory and computing power 

constraints; while also learning how to use XGBoost library for training and testing 

purposes. 

We also learned how to use important tools like command prompts to launch development 

environments and Github for code sharing collaboration. 

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Critical Mistakes 

Poor data exploration 

We performed very little data exploration on our own. We mainly depended on the data 

exploration that was done by other Kagglers. This resulted in sub-optimal solutions in 

our training and testing as we did not exclude outliers etc. 

Not preparing for system outages 

We faced one outage while using the Google Cloud Preemptible Instance (possibly due to 

high demand from other clients) which caused a key data file to become corrupted. The 

re-creation of this data file cost us over 5 hours of work. In the future, it would be 

preferable if the system was listening to “shut-down” signals that are sent by the 

platforms and took necessary steps to prevent the corruption of this data. 

Performing hyperparameter tuning too late 

In our process we initially performed feature selection using a set of parameters for 

XGBoost and then proceeded to hyperparameter tuning step. However, it became apparent 

that some features were being given lower scores because our initial set of parameters 

were not optimal for a high number of feature columns. Specifically, the depth of the 

trees were set to 6 in our initial feature selection; when this was increased to 22, it 

became apparent that the features that were originally dropped could have been good 

predictors. 

Further Exploration 

If we had more time and resources, we would have liked to undertake additional actions. 

Partial Fitting 

When faced with the memory problem we decided to use cloud services. However, another 

method would have been loading and processing the data in smaller batches. This would 

be a more scalable model and could even be used to create a cluster of cloud machines 

to perform operations in parallel. 

Multiple Models 

Although XGBoost is a very effective tool, it gives a single model (or in our case, 2 

models one for each week). We would like to explore the possibility of creating a 

larger number of models using different systems and seeing how they perform for 

different slices of data. We would then take some sort of weighted average of these 

predictions to reach our final prediction. 

As an extension to this idea, we would also perform parameter tuning across these 

various models to find optimal solutions for each one. 

Neural Networks 

We would also have like to approach this problem with a neural network solution to see 

the accuracy of the predictions and also the performance of the neural network solution 

vs the XGBoost tool. 

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