Replace String Value in Cell with Numerical Value

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chris1976
chris1976 2018-2-16
评论： chris1976 2018-3-1
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
  1 个评论
Guillaume
Guillaume 2018-2-16
Why does 'C.C4' get replaced by 2 and 'C.C5' by 3 (instead of 4 and 5 or something more logical)?

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采纳的回答

Stephen23
Stephen23 2018-2-19
编辑：Stephen23 2018-2-19
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

更多回答（1 个）

Guillaume
Guillaume 2018-2-16
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)
  1 个评论
chris1976
chris1976 2018-2-19
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

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