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Find only numeric strings on cellstr array.

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Ajpaezm 2021년 6월 15일
댓글: Ajpaezm 2021년 6월 15일
I'd like to know the index of the "numerical strings" within a cellstr array.
arr = {'123', 'Hola', 'my', 'String', '', '1453', 'stay'};
A correct output will give me index 1 and 6.
isnumeric contained within cellfun doesn't work well here, I'd have to use it in combination with something else but I don't know exactly what that might be.
Any help is appreciated.

채택된 답변

Krishna Sutar
Krishna Sutar 2021년 6월 15일
From my understanding you want to find the indexes of the strings in the cell string array that are numerical. Here is the code which might help you:
arr = {'123', 'Hola', 'my', 'String', '', '1453', 'stay'};
idx = find(~isnan(str2double(arr)))
isnumeric checks whether the datatype of the object is numeric, which in this case is string which would return false. Please refer to isnumeric and find for more information.
  댓글 수: 3
Ajpaezm 2021년 6월 15일
@Stephen Cobeldickthank you, I understand. Luckily, the array won't have any presence of them, but in case some weird stuff happens and indeed gets populated with it, I'll be sure to use your proposal.

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추가 답변(2개)

Walter Roberson
Walter Roberson 2021년 6월 15일
arr = {'123', 'Hola', 'my', 'String', '', '1453', 'stay'};
find(~cellfun(@isempty, regexp(arr, '^\d+$', 'once')))
ans = 1×2
1 6
find(matches(arr, lineBoundary + digitsPattern + lineBoundary))
ans = 1×2
1 6

Stephen 2021년 6월 15일
편집: Stephen 2021년 6월 15일
Writing regular expressions or pattern matching that robustly detects all valid number formats is not such a trivial task... it is more reliable to let MATLAB do the heavy lifting:
arr = {'123', 'Hola', 'my', 'String', '', '1453', 'stay', '-1.234', 'NaN', '9e-87'};
idx = strcmpi(arr,'NaN')|~isnan(str2double(arr))
idx = 1×10 logical array
1 0 0 0 0 1 0 1 1 1
ans = 1×5
1 6 8 9 10




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