Replace String Value in Cell with Numerical Value

Hi all

I like to replace a string value in a cell with a numerical value.

The cell looks like:

A1 = {-1,0,0,0,0,0,0;1,-1,0,0,-1,0,0;0,1,1,-1,0,0,0;0,1,1,-1,0,0,0;0,0,1,0,0,0,0;0,0,0,'C.C4',0,0,0;0,0,0,0,1,1,-1;0,0,0,0,0,1,0;0,0,0,0,0,0,'C.C5'}

I like to replace the string C.C4 and C.C5 with numerical values like: C.C4 = 2; C.C5 = 3;

I already burnt hours on this problem! Thanks a lot for your help (-:

Cheers, Chris

[Guillaume]

Why does 'C.C4' get replaced by 2 and 'C.C5' by 3 (instead of 4 and 5 or something more logical)?

Answer 1

[Stephen23]

A = {'Inf','C.C3','C.C2',1;'-Inf',1,'C.C5','Inf';'C.C4',0,0,'-Inf';0,0,1,'-Inf'};
idn = cellfun(@isnumeric,A); % identify numeric values.
out = nan(size(A));          % preallocate output matrix.
out(idn) = [A{idn}];         % allocate numeric values.
tmp = A(~idn);               % subset with char vectors.
vec = str2double(tmp);       % attempt to convert to numeric.
idx = isnan(vec);            % identify char not converted.
C = {'C.C2','C.C3','C.C4','C.C5','C.C6'};
V = [    10,   100,    34,    35,   100];
[idm,idc] = ismember(tmp(idx),C); % lookup table.
assert(all(idm),'Not in C:%s',sprintf(' %s,',C{~idm}))
vec(idx) = V(idc);
out(~idn) = vec

giving this numeric matrix:

out =
   Inf   100    10     1
  -Inf     1    35   Inf
    34     0     0  -Inf
     0     0     1  -Inf

An alternative to throwing an error for missing C.Cx strings would be to put a NaN in that position:

[idm,idc] = ismember(tmp(idx),C) % lookup table.
tmp = nan(size(idc));
tmp(idm) = V(idc(idm))
vec(idx) = tmp;
out(~idn) = vec

[chris1976]

thx a lot stephen! your solution works (-:

Answer 2

[Guillaume]

Identifying the char elements is easy. And once the rule for replacing them by numbers is known, replacing them is also easy:

toreplace = cellfun(@ischar, A1);
A1(toreplace) = num2cell((1:sum(toreplace(:))) + 1)  %arbitrary rule that replace char arrays by numbers 2, 3, 4, ...

After that you probably want

A1 = cell2mat(A1)

[chris1976]

Hi all! Thx for your answers. I couldn't solve my problem yet. I like to specify as follows:

My cell array looks for example like this (mixed string and numeric values out of xlsread):

A1 = {'Inf','C.C3','C.C2',1;'-Inf',1,'C.C5','Inf';'C.C4',0,0,'-Inf';0,0,1,'-Inf'}

I want to replace the following string values (variables) with numeric values for example:

C.C2 = 10 C.C4 = 34 C.C5 = 25 C.C6 = 100

And I like to change the string value "Inf" resp. "-Inf" to numeric Inf and -Inf (infinite and negativ infinite).

I tried with your solutions but couldn't do it - maybe because I specified my problem too little.

Hope you may help! Thx a lot in advance. Cheers, Chris