Python: how to sort a CSV file by some column(s)

Question

How can I sort a CSV file using Python code? The file should be sorted by one or more columns.

Answer 1

You can use Pandas module of Python to import your CSV file into a dataframe. You can sort the dataframe by any number of columns and then can export the sorted dataframe to a CSV file.

Here is an example. My CSV file 'test.csv' has the following data:

Name	Age	DOB
AA	29	1967
BB	12	1867
CC	45	1834
DD	34	1945
EE	38	2011
FF	17	1745
GG	22	1867
HH	12	1756
II	38	2000

You can try the following code to sort the CSV file. You can also use CSV module of Python instead of Pandas, but I prefer Pandas.

>>> import pandas as pd
>>> df = pd.read_csv('test.csv', sep=',') #Read CSV file and create a DataFrame
>>> df
  Name  Age   DOB
0   AA   29  1967
1   BB   12  1867
2   CC   45  1834
3   DD   34  1945
4   EE   38  2011
5   FF   17  1745
6   GG   22  1867
7   HH   12  1756
8   II   38  2000
>>> df1=df.sort_values(by=['Age'])  # sort by Age
  Name  Age   DOB
1   BB   12  1867
7   HH   12  1756
5   FF   17  1745
6   GG   22  1867
0   AA   29  1967
3   DD   34  1945
4   EE   38  2011
8   II   38  2000
2   CC   45  1834
>>> df1=df.sort_values(by=['Age','Name'])  # sort by Age and Name
  Name  Age   DOB
1   BB   12  1867
7   HH   12  1756
5   FF   17  1745
6   GG   22  1867
0   AA   29  1967
3   DD   34  1945
4   EE   38  2011
8   II   38  2000
2   CC   45  1834
>>> df1.to_csv('test.csv',index=False)  # write the sorted data to CSV

The output 'test.csv' now has the sorted data.

Name	Age	DOB
BB	12	1867
HH	12	1756
FF	17	1745
GG	22	1867
AA	29	1967
DD	34	1945
EE	38	2011
II	38	2000
CC	45	1834