python reading text file

Question

I have a text file, of which i need each column, preferably into a dictionary or list, the format is :

N       ID   REMAIN        VERS          
2 2343333   bana           twelve    
3 3549287   moredp       twelve        
3 9383737   hinsila           twelve           
3 8272655   hinsila           eight

I have tried:

crs = open("file.txt", "r")
for columns in ( raw.strip().split() for raw in crs ):  
    print columns[0]

Result = 'Out of index error'

Also tried:

crs = csv.reader(open(file.txt", "r"), delimiter=',', quotechar='|', skipinitialspace=True)
    for row in crs:
                   for columns in row:
                             print columns[3]

Which seems to read each char as a column, instead of each 'word'

I would like to get the four columns, ie:

2
2343333
bana
twelve

into seperate dictionaries or lists

Any help is great, thanks!

You use crs = csv.reader(open(file.txt", "r"), delimiter=',', quotechar='|', skipinitialspace=True) and have a CSV file with spaces as delimiter? Also print row[3] if this is the variable you get at each iteration, not columns[3]. — eumiro
– eumiro, Commented Sep 20, 2011 at 12:54
if i set delimiter to " " it produces the same output, i was just playing with the "," to see if i could make a change — Kilizo
– Kilizo, Commented Sep 20, 2011 at 12:57
Your first for loop works for me. No 'out of index error'. — senderle
– senderle, Commented Sep 20, 2011 at 13:05
@senderle i have a line of whitespace at the top, this explains it, how would i get rid of this? — Kilizo
– Kilizo, Commented Sep 20, 2011 at 13:10

senderle · Accepted Answer · 2011-09-20 13:15:54Z

19

This works fine for me:

>>> crs = open("file.txt", "r")
>>> for columns in ( raw.strip().split() for raw in crs ):  
...     print columns[0]
... 
N
2
3
3
3

If you want to convert columns to rows, use zip.

>>> crs = open("file.txt", "r")
>>> rows = (row.strip().split() for row in crs)
>>> zip(*rows)
[('N', '2', '3', '3', '3'), 
 ('ID', '2343333', '3549287', '9383737', '8272655'), 
 ('REMAIN', 'bana', 'moredp', 'hinsila', 'hinsila'), 
 ('VERS', 'twelve', 'twelve', 'twelve', 'eight')]

If you have blank lines, filter them before using zip.

>>> crs = open("file.txt", "r")
>>> rows = (row.strip().split() for row in crs)
>>> zip(*(row for row in rows if row))
[('N', '2', '3', '3', '3'), ('ID', '2343333', '3549287', '9383737', '8272655'), ('REMAIN', 'bana', 'moredp', 'hinsila', 'hinsila'), ('VERS', 'twelve', 'twelve', 'twelve', 'eight')]

edited Sep 20, 2011 at 13:15

answered Sep 20, 2011 at 13:09

senderle

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1 Comment

Kilizo Over a year ago

Thanks, you've made me realise that its the line of whitespace that is causing my out of index error, i think, how would i get rid of the line of whitespace?

utdemir · Accepted Answer · 2011-09-20 13:10:27Z

7

>>> with open("file.txt") as f:
...    c = csv.reader(f, delimiter=' ', skipinitialspace=True)
...    for line in c:
...        print(line)
... 
['N', 'ID', 'REMAIN', 'VERS', ''] #that '' is for leading space after columns.
['2', '2343333', 'bana', 'twelve', '']
['3', '3549287', 'moredp', 'twelve', '']
['3', '9383737', 'hinsila', 'twelve', '']
['3', '8272655', 'hinsila', 'eight', '']

Or, old-fashioned way:

>>> with open("file.txt") as f:
...     [line.split() for line in f]
...
[['N', 'ID', 'REMAIN', 'VERS'],
 ['2', '2343333', 'bana', 'twelve'],
 ['3', '3549287', 'moredp', 'twelve'],
 ['3', '9383737', 'hinsila', 'twelve'],
 ['3', '8272655', 'hinsila', 'eight']]

And for getting column values:

>>> l
[['N', 'ID', 'REMAIN', 'VERS'],
 ['2', '2343333', 'bana', 'twelve'],
 ['3', '3549287', 'moredp', 'twelve'],
 ['3', '9383737', 'hinsila', 'twelve'],
 ['3', '8272655', 'hinsila', 'eight']]
>>> {l[0][i]: [line[i] for line in l[1:]]  for i in range(len(l[0]))}
{'ID': ['2343333', '3549287', '9383737', '8272655'],
 'N': ['2', '3', '3', '3'],
 'REMAIN': ['bana', 'moredp', 'hinsila', 'hinsila'],
 'VERS': ['twelve', 'twelve', 'twelve', 'eight']}

edited Sep 20, 2011 at 13:10

answered Sep 20, 2011 at 12:58

utdemir

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1 Comment

Kilizo Over a year ago

so how would you read each value into a dictionary or list, so all the 1st column in a list and all the 2nd column in a list.

rajpython · Accepted Answer · 2014-02-26 12:23:15Z

1

How about this?

f = open("file.txt")

for i in f:
    k = i.split()
    for j in k:
        print j

answered Feb 26, 2014 at 12:23

rajpython

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Comments

daramarak · Accepted Answer · 2011-09-20 13:03:05Z

0

You could use a list comprehension like this:

with open("split.txt","r") as splitfile:
    for columns in [line.split() for line in splitfile]:
        print(columns)

You will then have it in a 2d array allowing you to group it any way you like it.

answered Sep 20, 2011 at 13:03

daramarak

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Comments

Jashu · Accepted Answer · 2014-02-26 12:06:10Z

just use a list of lists

import csv

columns = [[] for _ in range(4)]  # 4 columns expected

with open('path', rb) as f:
    reader = csv.reader(f, delimiter=' ')
    for row in reader:
        for i, col in enumerate(row):
            columns[i].append(col)

or if the number of columns needs to grow dynamically:

import csv

columns = []

with open('path', rb) as f:
    reader = csv.reader(f, delimiter=' ')
    for row in reader:
        while len(row) > len(columns):
            columns.append([])
        for i, col in enumerate(row):
            columns[i].append(col)

In the end, you can then print your columns with:

for i, col in enumerate(columns, 1):
    print 'List{}: {{{}}}'.format(i, ','.join(col))

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