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Collection of Python and R code modules to explore their differences and advantages over one another. Both are quite important for ML.

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R and Python Data Wrangling

Home of my Fall 2020 Honors project. Goal is to learn about key data science tools and compare and contrast the two key languages for it: R and Python.

Key differences between R and Python

R

+ ggplot2 is a good plotting library for R.
+ Importing datasets from a package and from a url. + Rmd files instead of Jupyter + MUCH BETTER wrangling functions within the tidyverse and dplyr. Chapter 4 was a pain with Python Pandas. Far too verbose.
+ Fitting models and graphing is much much simpler.

Python

+ Pandas is a huge component of Python Data Wrangling. Encompasses the data frame and csv reading for example.
+ No really good ggplot equivalent in Python. The libraries that are available feel like R anyway if they try to emulate ggplot2.
+ Jupyter Notebook (formally/now encompasses IPython Notebooks) + I use anaconda, which comes with a Python installation and a "in my opinion" better pip command, the conda command.
- YIKES. Fitting models and graphing in Python is a mess. There are several options that are not easy to use, especially if you are not a stats expert...

Notes/Comments on Exercises

Module 1 (8/17/2020)

Using Anaconda, installation video: https://www.youtube.com/watch?v=YJC6ldI3hWk

Jupytr Notebook contains IPython Notebooks: https://www.youtube.com/watch?v=HW29067qVWk

  • Navigate to git repo in powershell
  • Type command: jupyter notebook
  • Redirect to localhosted jupyter repo.

Pandas and file reading: https://realpython.com/pandas-python-explore-dataset/

Export to pdf works badly in Jupyter's gui, trying on the command line. Command line worked perfectly using:

jupyter nbconvert Chp1Exercises.ipynb --to pdf

Module 2 (8/17/2020)

Using Anaconda, installation video: https://www.youtube.com/watch?v=YJC6ldI3hWk

Jupytr Notebook contains IPython Notebooks: https://www.youtube.com/watch?v=HW29067qVWk

  • Navigate to git repo in powershell
  • Type command: jupyter notebook
  • Redirect to localhosted jupyter repo.

Pandas and file reading: https://realpython.com/pandas-python-explore-dataset/

Export to pdf works badly in Jupyter's gui, trying on the command line. Command line worked perfectly using:

jupyter nbconvert Chp1Exercises.ipynb --to pdf

Module 4 (9/04/2020)

Filtering in python based on multiple values: https://thispointer.com/python-pandas-select-rows-in-dataframe-by-conditions-on-multiple-columns/

Mutating and creating new columns in df with a for loop and iterrows(): https://stackoverflow.com/questions/56916916/pandas-calculations-across-rows-and-columns

Cut function in Pandas: https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.cut.html

Pd cut: https://stackoverflow.com/questions/45751390/pandas-how-to-use-pd-cut

To access and add dataframe:

body[] =

Module 5 (9/11/2020) Fitting models with statsmodels.api in Python: statsmodels.org/stable/gettingstarted.html

Scatterplots with facet grid using Seaborn: https://seaborn.pydata.org/generated/seaborn.FacetGrid.html

Deleting rows based on condition: https://stackoverflow.com/questions/18172851/deleting-dataframe-row-in-pandas-based-on-column-value

Reference table for linear regression model value access: https://www.statsmodels.org/stable/generated/statsmodels.regression.linear_model.RegressionResults.html#statsmodels.regression.linear_model.RegressionResults

Get confidence intervals from Python statsmodels: https://stackoverflow.com/questions/17559408/confidence-and-prediction-intervals-with-statsmodels/17560456

Is something wrong with your RMarkdown Knit positioning? It is probably your headers. Check that the number of # symbols you have is valid. Two is preferrable for exercise headings.

Module 6/7(9/20/2020)

R normals refernce: https://stat.ethz.ch/R-manual/R-devel/library/stats/html/Normal.html

Sorting columns by another column in Python Pandas: https://stackoverflow.com/questions/34347041/pandas-sort-a-column-by-values-in-another-column https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.sort_values.html

Seaborn lineplots: https://seaborn.pydata.org/generated/seaborn.lineplot.html

Seaborn graph gallery: https://seaborn.pydata.org/examples/index.html

Module 8/9(9/27/2020)

Guide to vectors, lists, and matricies in Python with NumPy: https://www.oreilly.com/library/view/machine-learning-with/9781491989371/ch01.html

Drop NA from dataframe Pandas: https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.dropna.html

Drop NA columns: https://stackoverflow.com/questions/45147100/pandas-drop-columns-with-all-nans

Select based on condition Pandas DF: https://chrisalbon.com/python/data_wrangling/pandas_selecting_rows_on_conditions/

Select all but one column: https://stackoverflow.com/questions/29763620/how-to-select-all-columns-except-one-column-in-pandas

Select from matrix numpy: https://thispointer.com/python-numpy-select-rows-columns-by-index-from-a-2d-ndarray-multi-dimension/

Ndarray to fill in values to specified matrix size: https://numpy.org/doc/stable/reference/generated/numpy.ndarray.html

Module 10/11(10/4/2020) Benchmarking in a Jupyter notebook: https://stackoverflow.com/questions/32565829/simple-way-to-measure-cell-execution-time-in-ipython-notebook %%timeit and %%time are now magic commands in Python built in!

Magic commands: https://ipython.org/ipython-doc/3/interactive/magics.html

Regex matching and compilation with re library in Python: https://docs.python.org/3/howto/regex.html

Module 12(10/11/2020) Used libraries: import pandas as pd import numpy as np import datetime from dateutil.relativedelta import relativedelta import pytz

Python solution powered by the datetime https://docs.python.org/3/library/datetime.html Convert string to date: https://stackabuse.com/converting-strings-to-datetime-in-python/ Python arithmetic on dates with relativedelta https://www.pythonprogramming.in/add-n-number-of-year-month-day-hour-minute-second-to-current-date-time.html Datedelta for arithmetic: https://pypi.org/project/datedelta/ RelativeDelta to calculate intervals between dates: https://www.odoo.com/forum/help-1/question/how-do-i-calculate-number-of-months-between-two-dates-9443 Alternate number of days between dates calculation: https://stackoverflow.com/questions/151199/how-to-calculate-number-of-days-between-two-given-dates Set primary index of pandas dataframe: https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.set_index.html Filtering dataframe on dates (didn't work fully): https://stackoverflow.com/questions/22898824/filtering-pandas-dataframes-on-dates First and last row of dataframe: https://stackoverflow.com/questions/36542169/extract-first-and-last-row-of-a-dataframe-in-pandas Timezones with pytz: http://pytz.sourceforge.net/ Misc lambda function examples: https://www.w3schools.com/python/python_lambda.asp

Module 13(10/18/2020) Good comparison of data reshaping with R and Python Pandas https://pandas.pydata.org/docs/getting_started/comparison/comparison_with_r.html Merging and combining in Pandas: https://pandas.pydata.org/pandas-docs/stable/user_guide/merging.html Count and Series to Dataframe conversions for problem 1: https://stackoverflow.com/questions/38933071/group-by-two-columns-and-count-the-occurrences-of-each-combination-in-pandas

Module 16(11/9/2020) Pandas read_html for web scraping: https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.read_html.html Beautiful Soup + Pandas: https://stackoverflow.com/questions/50633050/scrape-tables-into-dataframe-with-beautifulsoup (See answer 2, not the accepted answer) Mod_security workaround for 405 Forbidden errors: https://stackoverflow.com/questions/16627227/http-error-403-in-python-3-web-scraping?lq=1

Needed libraries:

Pandas for data frames

Requests for grabbing the remote csv

Numpy for np.arrays to interface with a data frame

Useful Resources

R Graphics Cookbook for Plots, Graphics, and Graphs. http://www.cookbook-r.com/Graphs/
Used to create textbooks using R markdown. https://bookdown.org

Presentation

See the final presentation directory to view the slides comparing R and Python.

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Collection of Python and R code modules to explore their differences and advantages over one another. Both are quite important for ML.

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