Prompting user input() and using regular expression

Question

I want to use regular expression to print all the text fragments in a list found in another text. Both texts are prompted by the user and the names (egg and egg_carton are just names, it's not about eggs). The following code prints an empty list. I think the problem is the re.compile part of the code, but I don't know how to fix this problem. I would like the code modified in it's form, not a completely other method of solving this problem. Appreciate it.

import re
egg= input()
egg_carton = input()
text_fragment = re.compile(r'(egg)')
find_all = text_fragment.findall(egg_carton)
print(find_all)

Can you provide some sample input (and the value of egg with that sample input)? — rst-2cv
– rst-2cv, Commented Jun 24, 2018 at 11:58
So if the user writes egg = up and egg_carton = upupupup the program should output [up, up, up, up] — Liviu Iosif
– Liviu Iosif, Commented Jun 24, 2018 at 12:01
Agree with @kabanus. If you want to look for the value of egg in egg_carton, then you need to use: text_fragment = re.compile(r'({0})'.format(egg)). The .format(egg) converts {0} to contain the value of egg. — rst-2cv
– rst-2cv, Commented Jun 24, 2018 at 12:04
Yes so if egg = "up", then re.compile(r'({0})').format(egg)) is equivalent to re.compile(r'(up)') — rst-2cv
– rst-2cv, Commented Jun 24, 2018 at 12:06
Look up string formatting with .format in the Python specifications for your version. — Jongware
– Jongware, Commented Jun 24, 2018 at 12:17

rst-2cv · Accepted Answer · 2018-06-24 12:12:45Z

2

If you want to look for the value of egg (i.e. egg = "up") in egg_carton (i.e. egg_carton = "upupupup"), then you need to use:

text_fragment = re.compile(r'({0})'.format(egg))

The .format(egg) converts {0} to contain the value of egg. Therefore, if egg = "up", it would be equivalent to:

text_fragment = re.compile(r'(up)')

Putting this all together:

import re
egg= raw_input()
egg_carton = raw_input()
text_fragment = re.compile(r'({0})'.format(egg)) # same as: re.compile(r'(up)')
find_all = text_fragment.findall(egg_carton)
print(find_all)

Gives me this output:

['up', 'up', 'up', 'up']

You can find more information on the "string".format() function in the Python3 docs: https://docs.python.org/3.4/library/functions.html#format

answered Jun 24, 2018 at 12:12

rst-2cv

1,1803 gold badges15 silver badges31 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Prompting user input() and using regular expression

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related