how to slice strings with the help of a list of tuples?

Question

I have a list of tuples as as follows:

list_1 = [(2,10), (3,13), (5,23)]

and also a list of strings as follows:

list_2 = [ATGCATGCGAGTGCGAGTGCGTGCGTGCAGTGCGAGTGC,
          ATCGTCGTCGACGTAGCTAGCTAGCTAGCTAGCTAS,
          ATGCGTACGATCGATCGATCGATCGATCGAGCTAGCTAGCT]

I want to slice the list of strings with the help of given tuple integer gaps. For example;

I want to slice the first string from indexes 2 and 10 and print out only the letters which belong to those indexes. So the result print will be as ‘GCATGCGAG’.

For the second string it should slice and select the indexes from 3-13.so the result should be ‘GTCGTCGACGTAG’. This should go on. Can somebody suggest me a code for this. Thanks in advance.

can you post your current code? – RomanPerekhrest Nov 25 '19 at 07:43 — RomanPerekhrest, Nov 25 '19 at 07:43
What you have tried so far ? – Nishant Nawarkhede Nov 25 '19 at 07:43 — Nishant Nawarkhede, Nov 25 '19 at 07:43
What have you tried? Have you done any research? – AMC Nov 25 '19 at 09:15 — AMC, Nov 25 '19 at 09:15

score 3 · Accepted Answer · answered Nov 25 '19 at 07:54

3

A straightforward solution is to zip the two lists and use tuple elements from one list as slice parameters for the other:

[l2[l1[0] : l1[1] + 1] for l1, l2 in zip(list_1, list_2)]
#['GCATGCGAG', 'GTCGTCGACGT', 'TACGATCGATCGATCGATC']

If the second element of a tuple were the next element after the end of the subsequence (which is a "normal" Python convention), you could get an even more elegant solution:

[l2[slice(*l1)] for l1, l2 in zip(list_1, list_2)]
#['GCATGCGA', 'GTCGTCGACG', 'TACGATCGATCGATCGAT']

answered Nov 25 '19 at 07:54

DYZ

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What if 2 list have different length ? – Nishant Nawarkhede Nov 25 '19 at 07:58
2

@NishantNawarkhede Then the problem would not have a well-defined solution, but `zip` would stop at the end of the shortest list. – DYZ Nov 25 '19 at 07:59

Mykola Zotko · Answer 2 · 2019-11-25T08:00:05.633

1

You can use the function map:

list_1 = [(2,10), (3,13), (5,23)]

list_2 = ['ATGCATGCGAGTGCGAGTGCGTGCGTGCAGTGCGAGTGC',
          'ATCGTCGTCGACGTAGCTAGCTAGCTAGCTAGCTAS',
          'ATGCGTACGATCGATCGATCGATCGATCGAGCTAGCTAGCT']

list(map(lambda idx, lst: lst[idx[0]: idx[1]+1], list_1, list_2))
# ['GCATGCGAG', 'GTCGTCGACGT', 'TACGATCGATCGATCGATC']

edited Nov 25 '19 at 08:00

answered Nov 25 '19 at 07:57

Mykola Zotko

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Yusuf Rıdvan SAVUT · Answer 3 · 2019-11-25T08:07:34.693

0

use it to do what you want: string[num1:num2]

To print them all, you need this:

for i in range(len(list_1)):
    print(list_2[i][list_1[i][0]:list_1[i][1] +1])

hopefully the problem is solved,

Have a Good Code :)

edited Nov 25 '19 at 08:07

answered Nov 25 '19 at 08:01

Yusuf Rıdvan SAVUT

51
3

score -1 · Answer 4 · answered Nov 25 '19 at 08:01

You can use list comprehension to achieve this :

list_3 = [item[list_1[int(index)][0]:list_1[int(index)][1]] for index,item in enumerate(list_2)]

Above code will take one element from list_2 to item and use it index and use that in list_1 and than slice item according to tuple of list_1.

How it work :

Take item one by one from list_2
take tuple from list_1 using index
slice item using tuple
store it in list_3

how to slice strings with the help of a list of tuples?

4 Answers4