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How to convert cell to cell array of character vectors.

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Blue
Blue on 5 Aug 2019
Answered: Blue on 14 Aug 2019
Hi,
So I have a basic table that looks like this but has over 60 000 rows:
A = [48.44, 48.16].';
B = ['A', 'B'].';
C = table(A, B);
The problem is that when I type unique(C.B) Matlab complains : Cell array input must be a cell array of character vectors.cell array of character vectors.
The commands class(btl_data.POLYGON) returns 'cell', and iscellstr(btl_data.POLYGON) returns 0. The commands char(C.B) and cellstr(C.B) fail (Element 1 is not a string scalar or character array. All elements of cell input must be string scalars or character arrays.)
So I dont know. I know this is really basic but nothing works. Column B really should be only characters.
Thoughts ?
  3 Comments
Stephen Cobeldick
Stephen Cobeldick on 14 Aug 2019
Note that this line
B = ['A', 'B'].';
is unlikely to be useful. Square brackets are a concatenation operator, so this
['A', 'B']
is exactly equivalent to this:
'AB'

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Accepted Answer

Adam Danz
Adam Danz on 13 Aug 2019
Edited: Adam Danz on 13 Aug 2019
At least one of the elements in btl_data.POLYGON is not a character vector. This demo below recreates the error.
A = [48.44, 48.16, 50].';
B = ['A', 'B', {5:10}].';
C = table(A, B);
unique(C.B)
% Error using cell/unique (line 85)
% Cell array input must be a cell array of character vectors.
To find the row numbers of table C that do not contain a char vector in column "B",
notChar_rowIndex = find(~cellfun(@ischar,C.B))
% ans =
% 3
Now you can look at those rows,
C(notChar_rowIndex,:)
  1 Comment
Guillaume
Guillaume on 13 Aug 2019
The error message says it's the first element that's problematic. There may be more so there's indeed value in getting these row indices.

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