nagasudhirpulla/python_wrldc_training

python sessions taken for WRLDC ETs

This code base is created with a goal of creating a knowledge base and uniform coding practices/habits among the developers therby aiding easier learning and collaboration

Software installed

• python - for running python
• Visual Studio Code / VS Code - code editor for python code
• git - source control system for managing python code

Topics covered

• Opened a folder in vs code
• Created a new python file
• print hello world using 'print' function in python
• commenting python code using '#'
• multi line commenting of python code using '''
• create variables (like strings and numbers) in python
• formatting strings with variable substitution in python
• if, else, elif in python
• while statement in python
• for statement in python
• intro to using git

pushing code to remote git repositories like GitHub

VS Code shortcuts

• Ctrl / to comment /uncomment code
• Alt Shift F to format the code
• Ctrl s to save files
• Ctrl + to zoom in, Ctrl - to zoom out
• Ctrl ~ to open/close command prompt

Lists in python

• find the length of list using 'len' function
• access a list item using its zero-indexed position
• append a value to a list using 'append' function
• append a list of values using 'extend' function
• insert a value at a desired position in the list using 'insert' function
• find the position of a value in a list using 'index' function
• create a list from another list using 'list comprehension' with filtering only numbers
• adding numbers to a list repeatedly using 'for' loop and 'append' functions
• sort the list of values using the 'sorted' function
• sort the list of values in descending order using the 'sorted' function with reverse input as True
• clone the original list to another variable using 'copy' module
• slicing the list
• clone the list using copy module
• reverse a list using 'reverse' function

using jupyter cells in python for easy debugging

• use # %% to create a jupyter cell in python code

type of variable

• use 'type' function to get the type of variable
• check the type of variable using 'isinstance' function

dictionaries in python

• create an example dictionary
• access all the keys of a dictionary using 'keys' function
• access all the values of a dictionary using 'values' function
• get all the values types of dictionary into an array using list comprehension
• inserting/editing a key-value pair in a dictionary
• accessing dictionary values

installing modules using pip install command

read command line inputs using the 'argparse' module

• get all desired command line inputs into an object

'Pandas' DataFrame Introduction

• Intro and terminologies in a pandas dataframe
• create a dataframe from list of lists
• read dataframe from a csv/excel file using 'read_csv', 'read_excel' function
• get all the column names of the dataframe using the 'columns' attribute
• get all the items of a specific column name
• filtering the rows of a dataframe based upon its column values

'Pandas' DataFrame concepts

• Pandas dataframe excel/csv loading options sheet_name, skiprows, skipfooter, nrows, usecols
• get the shape of dataframe in the form (nrows, ncols) using shape attribute
• Pandas export csv or excel using 'to_csv', 'to_excel' methods
• using iloc function to access a cell of dataframe by its index adress
• using iloc function to access a subset of dataframe by its index and column adress ranges
• pandas loc function to access dataframe data by specifying the row index values or column values
• make a column as index in a pandas DataFrame
• calculate average value of a dataframe column using mean() function
• calculate sum of a dataframe column using sum() function
• calculate aggregation of dataframe using 'for' loop
• create a new column in a dataframe

'Matplotlib' module for plotting

• Basic line plot
• set title for the plot
• set label to x and y axes
• enable legends for the plot
• control the location of legends in the plot
• save the figure as png/pdf/jpg using savefig function
• changing color of the line plot
• changing linestyle can be 'solid', 'dashed', 'dashdot', 'dotted', 'None'
• plot markers in the plot
• control plot markers style and size

Multiple plots in one figure

• Multiple lines in one plot using ax.plot function
• use subplots function to create multiple plots in one figure
• iterate through each axis through reshape
• set the figure title

sizing the plots

• using figsize option in subplots function to control size in inches

centering of matplotlib axes so that 0,0 point is in the middle of the figure

• hiding/changing the color of spines
• setting the position of spines

Python session on 24 Jul 2020, day 3

functions

functions and variables in diffrerent files and folders for implementing Separation of Concerns paradigm

using glob module for iterating files of a folder

• iterate through all the files of a folder
• iterate through all the files of a desired file extension in a folder

read and write text files

• using read mode, write mode, append mode while reading and writing files

datetime module in python

• get the current time
• create a desired datetime object using dt.datetime function
• using strftime to print datetime in a desired format like %d-%m-%Y %H:%M:%S
• using strptime to derive datetime object from string
• convert string type pandas dataframe column to datetime column
• access the components of a datetime object

timedeltas in datetime module

• create a desired time interval using dt.timedelta function
• get the difference between 2 datetimes
• access the components of a timedelta object
• get the total seconds in the time span using total_seconds function
• add time period to existing time period

using pyinstaller to deploy a python script as an executable

using smtplib module to send mail from posoco mail id

using psycopg2 module to interface with a postgreSQL database