Use an array containing indexes to extract a subset of larger array

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Scorp
Scorp 2022-7-15
评论： Jeffrey Clark 2022-7-15
largeArray = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]
indexes = [5,9,16]
% use the indexes array to extract 3 elements at each index in the largeArray to yield:
subSetArray = [5,6,7 ; 9,10,11; 16,17,18]
  1 个评论
Jeffrey Clark
Jeffrey Clark 2022-7-15
@Scorp, attack problems like this by looking at what you have and then what you want. I won't give you the answer here:
>>largeArray = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]
largeArray =
Columns 1 through 17
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Columns 18 through 20
18 19 20
>>indexes = [5,9,16]
indexes =
5 9 16
>>subSetArray = [5,6,7 ; 9,10,11; 16,17,18]
subSetArray =
5 6 7
9 10 11
16 17 18
>>note = indexes' % apostrophy converts arrays (look it up)
note =
5
9
16
>>also = 2+indexes' % compare with subSetArray
also =
7
11
18

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采纳的回答

Voss
Voss 2022-7-15
Ran in:
largeArray = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]
largeArray = 1×20
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
indexes = [5,9,16]
indexes = 1×3
5 9 16
% use the indexes array to extract 3 elements at each index in the largeArray to yield:
% subSetArray = [5,6,7 ; 9,10,11; 16,17,18]
subSetArray = largeArray(indexes(:)+(0:2))
subSetArray = 3×3
5 6 7 9 10 11 16 17 18
Make sure you don't go off the end of largeArray:
indexes = [5,9,19]
indexes = 1×3
5 9 19
subSetArray = largeArray(indexes(:)+(0:2))
Index exceeds the number of array elements. Index must not exceed 20.

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