python parse and get more input from line

Question

I need to parse a text file and get output and add them to list.

    with open(qwer.txt, 'r') as my_file:
        a = my_file.readlines()
        for line in a:
            for part in line.split():
                if "color=" in part:
                    p1 = part.split('=')[1] 
                    print(p1)
                    list1 = []  
                    p1.append(list1)

so, i have a line where i have two/more "color=" on same line and i need output to get both the colors:

my color=red and my color=green

my desired output is:

red
green

and i need to add them to a list seperately as ['red','green'] .please help! answers will be appreciated.

hjpotter92 · Accepted Answer · 2014-07-06 08:09:01Z

5

You can of course, use regex:

import re
str = "my color=red and my color=green"
p = r'color=([a-z]+)'
x = re.findall(p, str)

answered Jul 6, 2014 at 8:09

hjpotter92

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4 Comments

adarshram Over a year ago

i need to add to list,how should i do it?

hjpotter92 Over a year ago

@adarshram The variable x WILL be a list. You can read about re.findall() here

adarshram Over a year ago

how should i open my files and perform this operation rath?er than a single str

hjpotter92 Over a year ago

@adarshram After for line in a:, use line instead of str

pts · Accepted Answer · 2014-07-06 09:11:48Z

3

Your solution is almost correct, you print the correct lines. Here is how to save them to a list:

result = []
with open('qwer.txt') as my_file:
    for line in my_file:
        for part in line.strip().split():
            if "color=" in part:
                p1 = part.split('=')[1] 
                result.append(p1)

If you need a list of lists, do it like this:

result = []
with open('qwer.txt') as my_file:
    for line in my_file:
        values = []
        for part in line.strip().split():
            if "color=" in part:
                p1 = part.split('=')[1] 
                values.append(p1)
        if values:
            result.append(values)

edited Jul 6, 2014 at 9:11

answered Jul 6, 2014 at 8:13

pts

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2 Comments

mmdanziger Over a year ago

I'd do line.strip().split() , I doubt if he wants "red\n" in his list.

pts Over a year ago

Indeed, added the .strip().

Elazar · Accepted Answer · 2014-07-06 08:17:33Z

2

Perhaps you can do it without regex:

parts = itertools.chain.from_iterable(line.split() for line in my_file)
colors = [part.split('color=')[1] for part in parts if part.startswith('color=')]

Although regex do seem to fit here best.

answered Jul 6, 2014 at 8:17

Elazar

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Comments

Avinash Raj · Accepted Answer · 2014-07-06 09:32:58Z

1

Most probably we should avoid using groups. You could get the value of color through lookbehind,

>>> import re
>>> str = 'my color=red and my color=green'
>>> m = re.findall('(?<=color=)\S+', str)
>>> m
['red', 'green']

edited Jul 6, 2014 at 9:32

answered Jul 6, 2014 at 9:16

Avinash Raj

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