Python formatting elements in an array with regex

Question

Using Python 2.6.6, I'm trying to format each element in a list using regex.

Example of elements in an array:

test1;apple;-fgnsldfgsbfdgb
test2;watermelon;-iwerunvfgkjsfg
test3;orange;wervxddgjbdhnf

I'd like to format the text to just grab what is in between the semicolons ;

apple
watermelon
orange

The regex to capture that is the following:

(?<=\;)(.*?)(?=\;)

I tried different variations of the following code:

for member in fruits:
    parseFruit = re.compile(member)
    member = member.sub( (\.),((?<=\;)(.*?)(?=\;)) )
    print("Fruit: ", member)

Nothing seems to work...

Andrej Kesely · Accepted Answer · 2018-07-10 15:58:56Z

2

import re

s = """test1;apple;-fgnsldfgsbfdgb
test2;watermelon;-iwerunvfgkjsfg
test3;orange;wervxddgjbdhnf"""

fruits = re.findall(r';(.*?);', s)

for fruit in fruits:
    print('Fruit: %s' % fruit)

#fruits is ['apple', 'watermelon', 'orange']

Output:

Fruit: apple
Fruit: watermelon
Fruit: orange

edited Jul 10, 2018 at 15:58

answered Jul 10, 2018 at 15:36

Andrej Kesely

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2 Comments

Awsmike Over a year ago

Sorry, I initially wrote lists in the title but it should have been array. I'm not sure if this changes anything but when I tried it, it prints it fine but the change doesn't keep

Andrej Kesely Over a year ago

In variable fruits you have ['apple', 'watermelon', 'orange']

The fourth bird · Accepted Answer · 2018-07-10 16:19:26Z

1

For your example data, instead of sub you can use search without a capturing group to get the first match.

(?<=;).*?(?=;)

fruits = ['test1;apple;-fgnsldfgsbfdgb',
'test2;watermelon;-iwerunvfgkjsfg',
'test3;orange;wervxddgjbdhnf']

for member in fruits:
    print ("Fruit: " + re.search("(?<=;).*?(?=;)", member).group(0))

Demo

If you want to use sub, you could match from the beginning of the string till the first occurence of ; and then als match that. Or match the last occurence of ; till the end of the string. Then replace that with an empty string.

^[^;]+;|;[^;]+$

for member in fruits:
    print("Fruit: " + re.sub(r'^[^;]+;|;[^;]+$', '', member))

Demo

edited Jul 10, 2018 at 16:19

answered Jul 10, 2018 at 15:38

The fourth bird

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5 Comments

Awsmike Over a year ago

Sorry, I initially wrote lists in the title but it should have been array. I'm not sure if this changes anything but when I tried it, it prints it fine but the change doesn't keep.

Awsmike Over a year ago

This works great! I had to add a "member =" instead of the "print" to keep the change, thank you!

Awsmike Over a year ago

Actually when I do a print(fruits) it prints it the original way... is there a write or save command I'm missing ?

The fourth bird Over a year ago

@Awsmike In the example the result of each operation is printed but fruits itself is not modified. If you want to change fruits you might use map (Demo) or store the result in a new list (Demo)

Awsmike Over a year ago

Thank You, I ended up doing just that, creating a new list and using newlist.append(member) for anyone who was interested...

Shikhar Goel · Accepted Answer · 2018-07-10 15:49:17Z

0

Alternatively, instead of using regex you can use the split function

FruitList= ['test1;apple;-fgnsldfgsbfdgb', 'test2;watermelon;-iwerunvfgkjsfg', 'test3;orange;wervxddgjbdhnf']
Fruits= [i.split(';')[1::2] for i in FruitList]

[['apple'], ['watermelon'], ['orange']]

answered Jul 10, 2018 at 15:49

Shikhar Goel

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