CODEWITHSUNDEEP
pythonlistcsvdictionary
Luke
Luke

Reputation: 79

CSV file handling in python

I have two csv files in the following format:

First file (data.csv):-

1,red
3,blue
4,green
2,gray
5,black

Second file (text.csv):-

1
3
2
4

My goal is to read second file (text.csv) and store the numbers probably in a list. Then I want to locate the colors that correspond to these numbers in first file (data.csv).

Hence, my final output should look something like:

1,red
2,gray
3,blue
4,green

I want to consider the use of dictionary but can't seem to understand how I will do it.

Upvotes: 1

Views: 367

Answers (3)

Paweł Kordowski
Paweł Kordowski

Reputation: 2768

This should work:

D = {}
with open('data.cvs') as f:
    for line in f:
        x, y = line.split(',')
        D[int(x)] = y

print D[1]

Upvotes: 0

Hugh Bothwell
Hugh Bothwell

Reputation: 56654

Using the csv module can save you some headaches; try

import csv
import sys

# version compatibility shim!
if sys.hexversion < 0x3000000:
    # Python 2.x
    opencsv = lambda f: open(f, mode="rb")
else:
    # Python 3.x
    opencsv = lambda f: open(f, newline="")

# read color data to a dictionary
with opencsv("data.csv") as inf:
    color = {int(num):col for num,col in csv.reader(inf)}

# do translation
with opencsv("text.csv") as inf:
    for num, in csv.reader(inf):
        num = int(num)
        print("{},{}".format(num, color[num]))

which produces

1,red
3,blue
2,gray
4,green

(same order as text.csv file)

Upvotes: 4

Lo&#239;c
Lo&#239;c

Reputation: 11943

#First populate the data dictionnary with data.csv file :
data = {}
with open('data.csv', 'r') as f:
    for line in f:
        try:
            index, value = line.split(',')
            data[index.replace('\r','').strip()] = value.replace('\r','').strip()
        except Exception as e:
            print('[!] Error hanling data line : %s - %s' % (line, e))

#Then compare the second file :
with open('text.csv', 'r') as f:
    for line in f:
        try :
            line = line.replace('\r','').strip()
            print('%s => %s' % (line, data[line]))
        except Exception as e:
            print('[!] Error finding %s in data - %s' % (line, e))

Upvotes: 1

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