# Get number after colon

3 views (last 30 days)
Dion Theunissen on 28 Jul 2021
Commented: Peter Perkins on 29 Jul 2021
I have a text with numbers column in a table. Now i want to only select the numbers after a colon (:)
I have no idea where to start, kan anyone help me? The table looks like this:
Now i want to check column 1 and read only the numbers behind a :
So row 1 I need 34.94, skip untill row 5, get 34.94 and so on.
Cris LaPierre on 28 Jul 2021
Please share the code you use to import this data into MATLAB.

DGM on 29 Jul 2021
Edited: DGM on 29 Jul 2021
I don't know that I'd bother trying to directly operate on the table. Maybe there are tools that make that easier, but I never use tables. If the relevant column is extracted as a cell vector of chars or as a column vector of strings, then regexp() can be used:
extracted = {'blah blah blah (blah): 23.345 blah blah blah';
'blah blah blah (blah):23.34 blah 123 blah';
'blah blah blah'}
extracted = 3×1 cell array
{'blah blah blah (blah): 23.345 blah blah blah'} {'blah blah blah (blah):23.34 blah 123 blah' } {'blah blah blah' }
out = regexp(extracted,'(?<=: *)[0-9]+(\.[0-9]+)?','match');
format compact; celldisp(out) % just for web display
out{1}{1} = 23.345 out{2}{1} = 23.34 out{3} = {}
... at which point it can be inserted into the table or whatever else is required for further processing. If you want a numeric vector:
out = cellfun(@str2double,out,'uniform',false);
out(cellfun(@isempty,out)) = {0}; % replace empty elements with zero (or use NaN if you want)
out = vertcat(out{:})
out = 3×1
23.3450 23.3400 0
Peter Perkins on 29 Jul 2021
DGM, you are correct. This is what dot subscripting on tables is for:
x = t.X;
<lengthy multiple-line computation on x to create y>
t.Y = y;
It may be that the computations are short enough that you can just do the subscripting in-line:
t.Y = <some calculation on t.X>
And of course this all assumes that y is the same length as x.

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