Reading CSV file from stdin in Python and modifying it

Question

I need to read csv file from stdin and output the rows only the rows which values are equal to those specified in the columns. My input is like this:

 2
 Kashiwa
 Name,Campus,LabName
 Shinichi MORISHITA,Kashiwa,Laboratory of Omics
 Kenta Naai,Shirogane,Laboratory of Functional Analysis in Silico
 Kiyoshi ASAI,Kashiwa,Laboratory of Genome Informatics
 Yukihide Tomari,Yayoi,Laboratory of RNA Function

My output should be like this:

 Name,Campus,LabName
 Shinichi MORISHITA,Kashiwa,Laboratory of Omics
 Kiyoshi ASAI,Kashiwa,Laboratory of Genome Informatics

I need to sort out the people whose values in column#2 == Kashiwa and not output first 2 lines of stdin in stdout.

So far I just tried to read from stdin into csv but I am getting each row as a list of strings (as expected from csv documentation). Can I change this?

 #!usr/bin/env python3

 import sys
 import csv

 data = sys.stdin.readlines()

 for line in csv.reader(data):

      print(line)

Output:

 ['2']
 ['Kashiwa']
 ['Name', 'Campus', 'LabName']
 ['Shinichi MORISHITA', 'Kashiwa', 'Laboratory of Omics']
 ['Kenta Naai', 'Shirogane', 'Laboratory of Functional Analysis in 
 Silico']
 ['Kiyoshi ASAI', 'Kashiwa', 'Laboratory of Genome Informatics']
 ['Yukihide Tomari', 'Yayoi', 'Laboratory of RNA Function']

Can someone give me some advice on reading stdin into CSV and manipulating the data later (outputting only needed values of columns, swapping the columns, etc.,)?

Answer 1

This is one approach.

Ex:

import csv

with open(filename) as csv_file:
    reader = csv.reader(csv_file)
    next(reader) #Skip First Line
    next(reader) #Skip Second Line
    print(next(reader)) #print Header
    for row in reader:
        if row[1] == 'Kashiwa':   #Filter By 'Kashiwa'
            print(row)

Output:

['Name', 'Campus', 'LabName']
['Shinichi MORISHITA', 'Kashiwa', 'Laboratory of Omics']
['Kiyoshi ASAI', 'Kashiwa', 'Laboratory of Genome Informatics']

Answer 2

Use Pandas to read your and manage your data in a DataFrame

import pandas as pd
# File location
infile = r'path/file'
# Load file and skip first two rows
df = pd.read_csv(infile, skiprows=2)
# Refresh your Dataframe en throw out the rows that contain Kashiwa in the campus column
df = df[df['campus'] != 'Kashiwa']

You can perform all kinds edits for example sort your DataFrame simply by:

df.sort(columns='your column')

Check the Pandas documentation for all the possibilities.

Answer 3

 #!usr/bin/env python3
 import sys
 import csv

 data = sys.stdin.readlines()  # to read the file
 column_to_be_matched = int(data.pop(0)) # to get the column number to match
 word_to_be_matched = data.pop(0) # to get the word to be matched in said column
 col_headers = data.pop(0) # to get the column names
 print(", ".join(col_headers)) # to print the column names
 for line in csv.reader(data):
     if line[column_to_be_matched-1] == word_to_be_matched: #while it matched
        print(", ".join(line)) #print it