Question

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Is there a way to substring a string in Python?

I have a string in the form ‘AAAH8192375948’. How do I keep the first 5 characters of this string, and strip all the rest? Is it in the form l.strip with a negative integer? Thanks.

Answer 1

A string in Python is a sequence type, like a list or a tuple. Simply grab the first 5 characters:

 some_var = 'AAAH8192375948'[:5]
 print some_var # AAAH8

The slice notation is [start:end:increment] — numbers are optional if you want to use the defaults (start defaults to 0, end to len(my_sequence) and increment to 1). So:

 sequence = [1,2,3,4,5,6,7,8,9,10] # range(1,11)

 sequence[0:5:1] == sequence[0:5] == sequence[:5] 
 # [1, 2, 3, 4, 5]

 sequence[1:len(sequence):1] == sequence[1:len(sequence)] == sequence[1:]
 # [2, 3, 4, 5, 6, 7, 8, 9, 10]

 sequence[0:len(sequence):2] == sequence[:len(sequence):2] == sequence[::2]
 # [1, 3, 5, 7, 9]

strip removes a character or set of characters from the beginning and end of the string – entering a negative number simply means that you are attempting to remove the string representation of that negative number from the string.