How to find a string in text and return the string from text?

manpreet Best Answer 3 years ago

I need find a string which already has special chars removed. So, I want to do is to find that string in a sentence and return the string with special chars. Ex: string = France09

Sentence : i leaved in France'09.

now I did re.search('France09',sentence), it will return True or False. But I want to get the output as France'09.

Can any one help me.

manpreet 3 years ago

From the docs (https://docs.python.org/2/library/re.html#re.search), search is not returning True or False:

Scan through string looking for the first location where the regular expression pattern produces a match, and return a corresponding MatchObject instance. Return None if no position in the string matches the pattern; note that this is different from finding a zero-length match at some point in the string.

manpreet 3 years ago

you are creating a new set and assign it to x here

x = x | set([4, 5, 6])

from here on y is independent of x (they are the names of different sets).

on the other hand in-place assignment in your first example does not create a new set; it just modifies the current instance in

x |= set([4, 5, 6])

now y still refers to the same set as x. you can see the difference by printing

 print(id(x))
 print(id(y))

before and after the assignments.

it may be instructive to visualize the difference on pythontutor.com.

everything i said above is valid for mutable objects (e.g. sets). for immutable objects the in-place assignments behave just like the 'normal' assignments; i.e. for x an int: x += 1 is the same as x = x + 1.