Convert nonuniform cell array to numeric array - matlab

Question

I am using xlsread in MATLAB to read in sheets from an excel file. My goal is to have each column of the excel sheet read as a numeric array. One of the columns has a mix of numbers and numbers+char. For example, the values could be 200, 300A, 450, 500A, 200A, 100. here is what I have so far:
[num, txt, raw] = xlsread(fileIn, sheets{ii}); % Reading in each sheet from a for loop
myCol = raw(:, 4) % I want all rows of column 4
for kk=1:numel(myCol)
if iscellstr(myCol(kk))
myCol(kk) = (cellfun(#(x)strrep(x, 'A', ''), myCol(kk), 'UniformOutput', false));
end
end
myCol = cell2mat(myCol);
This is able to strip off the char from the number but then I am left with:
myCol =
[200]
'300'
[450]
'500'
'200'
[100]
which errors out on cell2mat with:
cell2mat(myCol)
??? Error using ==> cell2mat at 46
All contents of the input cell array must be of the same data type.
I feel like I am probably mixing up () and {} somewhere. Can someone help me out with this?

Answer 1

Let me start from reading the file
[num, txt, raw] = xlsread('test.xlsx');
myCol = raw(:, 4);
idx = cellfun(#ischar,myCol ); %# find strings
data = zeros(size(myCol)); %# preallocate matrix for numeric data
data(~idx) = cell2mat(myCol(~idx)); %# convert numeric data
data(idx) = str2double(regexprep(myCol(idx),'\D','')); %# remove non-digits and convert to numeric

Answer 2

The variable myCol is initially a cell array containing both numbers and strings, something like this in your example:
myCol = {200; '300A'; 450; '500A'; '200A'; 100};
The steps you have to follow to convert the string entries into numeric values is:
Identify the cell entries in myCol that are strings. You can use a loop to do this, as in your example, or you can use the function CELLFUN to get a logical index like so:
index = cellfun(#ischar,myCol);
Remove the letters. If you know the letters to remove will always be 'A', as in your example, you can use a simple function like STRREP on all of your indexed cells like so:
strrep(myCol(index),'A','')
If you can have all sorts of other characters and letters in the string, then a function like REGEXPREP may work better for you. For your example, you could do this:
regexprep(myCol(index),'\D','')
Convert the strings of numbers to numeric values. You can do this for all of your indexed cells using the function STR2DOUBLE:
str2double(regexprep(myCol(index),'\D',''))
The final result of the above can then be combined with the original numeric values in myCol. Putting it all together, you get the following:
>> index = cellfun(#ischar,myCol);
>> result(index,1) = str2double(regexprep(myCol(index),'\D',''));
>> result(~index) = [myCol{~index}]
result =
200
300
450
500
200
100