Selecting DataFrame columns

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dataframe_select_columns

Skill - Vertically slicing a DataFrame by column names

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Skills Required

Please make sure to have all the skills mentioned above to understand and execute the code mentioned below. Go through the above skills if necessary for reference or revision

Pandas is a python library.
DataFrame is a data structure provided by the pandas library.

Please go through Pandas DataFrame Basics to learn the basics of pandas DataFrame.

In this post, we will learn how to select only desired columns of a dataframe

Instructions to run the codes below

  • Create a folder and place the csv file used in this post from here
  • Open the folder in Visual Studio Code
  • Create and work on python files in this folder

The excel files should look like the image below
excel_file_illustration

Suppose we want to get a single column data say column ‘A’ from a dataframe df, then we call df['A']. This will return a pandas Series. This is because each column data of a dataframe is a Series.

Suppose we want to get data of multiple columns data say columns ‘A’, ‘B’, ‘C’ from a dataframe df, then we call df[['A','B','C']]. This will return a pandas DataFrame.

Example

import pandas as pd

# read the csv file into a dataframe named df
df = pd.read_csv('gen_schedules.csv')

# This dataframe contains many columns, but now we will select only KAPS, KHARGONE-I columns
filteredDf = df[["KAPS", "KHARGONE-I"]]
print(filteredDf)

print(type(filteredDf))
# this will print pandas.core.frame.DataFrame

# select only KHARGONE-I data
kharData = df["KHARGONE-I"]
print(kharData)

print(type(kharData))
# this will print pandas.core.series.Series

Notice that the type of kharData is Series and the type of filteredDf is DataFrame. This is because kharData variable is obtained by getting only a single column of the main dataframe df

Video

Video for this post can be found here

Online Interpreter

Although we recommend to practice the above examples in Visual Studio Code, you can run these examples online at https://www.tutorialspoint.com/execute_python_online.php

References

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