Open–Source Python Tools for Environmental Data Processing ...

Open–Source Python Tools for Environmental Data Processing, Analysis, and Visualization

Open –Source Python Tools for Environmental Data Processing, Analysis, and Visualization

9/17/2019

Michael J. MurphyEnvironmental Data Analyst/ Data Scientist and Senior Staff Geologist

Terraphase Engineering Inc.

OVERVIEW


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• The Python programming language

• Why Python?

• Python data analysis basics

• Case studies

• Review

PYTHON* IS A MODERN PROGRAMMING LANGUAGE THAT IS ESPECIALLY USEFUL FOR QUANTITATIVEDATA ANALYSIS AND SCIENTIFIC PROGRAMMING


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*Python is named after Monty Python, not Pythonidae.

!=+

WHY PYTHON INSTEAD OF EXCEL?


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vs.

BASIC PYTHON DATA TOOLS


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• DataFrame table structures • Access, process, analyze, export and visualize data

• Vast collection of functions for array operations• Quantitative analysis

• High-level plotting functions• Can produce publication-quality data visualizations• Works seamlessly with Python data tools such as NumPy, pandas

EXAMPLE: PANDAS DATAFRAMES


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Key Values

Index

EXAMPLE: PANDAS DATAFRAMES


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Original wide-format table:

Melted long-format table:

EXAMPLE: NUMPY OPERATIONS


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Vectorize function:

Draw random values:

Define function to calculate ion balance:

EXAMPLE: PLOTTING WITH MATPLOTLIB


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A very basic example of a Matplotlib plot:


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CASE STUDIES


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CASE STUDY: MACHINE LEARNING ANALYSIS OF VOC DISTRIBUTION INFRACTURED AQUIFER

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ML STUDY PT. 1 – PRINCIPLE COMPONENT ANALYSIS

DATA CONSISTS OF DEPTH, DIP AND STRIKE, VOCS, AND DESCRIPTION


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DATA IS CONVERTED TO A NUMERICAL ARRAY OR MATRIX


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Original data table:

Numerical data in array:

Categorical data as target values:

DATA IS SCALED, THEN DECOMPOSED INTO TWO PRINCIPLE COMPONENTS(EIGENVECTORS)


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Scale data:

Transform data with PCA:

COMPONENT 2 IS PLOTTED AGAINST COMPONENT 1, AND TARGET NAMES ARE ASSIGNED


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COMPONENT 2 IS PLOTTED AGAINST COMPONENT 1, AND TARGET NAMES ARE ASSIGNED


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Target categories show clustering:


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ML STUDY PT. 2 – K-MEANS CLUSTERING

DIP AND VOCS ARE SELECTED FROM SAME DATA AS AN ARRAY


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Same dataset as PCA example:

Select dip and VOC columns as array:

DATA IS SCALED AND A NEW VECTOR CREATED WITH FOUR K-MEANS CLUSTERS


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Create K-means pipeline:

Fit and predict four clusters:

LABELS ARE ADDED, AND EACH CLUSTER LABEL COUNTED


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Original data:

Two new columns with cluster labels:

Counts of cluster labels:

CLUSTERS ARE PLOTTED WITH DEPTH


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Clusters plotted with depth:

THE CLUSTER COUNTS INDICATE THAT A HIGHER PERCENTAGE OF LOW-ANGLE FEATURES HAVE HIGHVOCS


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Count = 71

Count = 30Count = 29

Count = 48


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BOTH UNSUPERVISED METHODS INDICATE CLUSTERING BETWEEN VARIABLES

Count = 71

Count = 30

Count = 29

Count = 48

CASE STUDY: WELL TRANSDUCER DATA PROCESSING AND VISUALIZATION


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DATA FROM A SINGLE TRANSDUCER CONTAINS NEARLY 70,000 DATA POINTS


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Data collected every 1m; ~70,000 records:

SEVERAL LARGE OUTLIERS ARE PRESENT WHERE TRANSDUCER WAS MOVED, ETC.


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Large artificial outliers:

OUTLIERS ARE ITERATIVELY REPLACED WITH INTERPOLATED VALUES


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Interpolate and impute outliers:

THE RESULTING HYDROGRAPH IS MUCH MORE READABLE


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Hydrograph with outliers replaced:

THE PROCESSED DATASET IS THEN RESAMPLED TO THE MEAN HOURLY VALUE


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Resample dataset to the hourly mean:

Data is reduced by ~98% to ~1,200 records:

THE PROCESSED AND REDUCED DATASET CONTAINS THE ESSENTIAL INFORMATION


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Hydrograph of reduced dataset:

BY ITERATIVELY REPLACING ARTIFICIAL OUTLIERS AND REDUCING THE SIZE OF THE DATASET, WHATWOULD TAKE SEVERAL HOURS IN EXCEL IS ACCOMPLISHED IN LESS THAN 1 MINUTE


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REVIEW AND FURTHER TOPICS


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• Python presents a comprehensive and free open-source toolkit for data processing, analysis and visualization– Python libraries, such as NumPy, pandas, Matplotlib, Seaborn, and Jupyter Notebook

– Developed by universities, scientists, independent developers

– Libraries can be used together to process, analyze, and visualize groundwater and environmental data

– More accurate, powerful, and repeatable than Excel, etc.

– Range of applications from simple EDA to complex ML studies

• Python can also be used to interact with other software and codes– FloPy- MODFLOW library

– PHREEQPY- PHREEQC library

– ArcPy, Python API- Interact and script functions within ESRI’s ArcGIS suite

THANK YOU! QUESTIONS?


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Please feel free to contact me at [email protected] if you have

any questions we cannot get to, or find me around the conference.

mailto:[email protected]

CASE STUDY: EDA TO VISUALIZE METALS DISTRIBUTIONS WITH DEPTH


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• Metals data from soil samples– Potentially contaminated site

– Arsenic is primary COC

– Examine distribution of As with depth to determine possible outliers

• EDA with ‘Seaborn’ Python library, Jupyter Notebooks

– Seaborn: High-level statistical visualization tools built on Matplotlib

– Works seamlessly with pandas DataFrames

– Allows rapid EDA

– Produce publication-quality visualizations

– Jupyter Notebooks: Edit and compile code, view inline plots



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Wide-format tableof metals data:



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Plot all metals against depth:



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Highlight arsenic results:



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Box and scatter plot of arsenic vs. depth:



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Violin and scatter plot of arsenic vs. depth:



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Open–Source Python Tools for Environmental Data Processing ...

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