Error assigning VariableNames using array2table + creating concatenated strings

Question

When attempting to assign VariableNames to table columns when using array2table I am getting the error:

Error using array2table (line 62)
The VariableNames property must be a cell
array, with each element containing one
nonempty string.

This error however only occurs when using a cell-array constructed using strcat or sprintf, for example:

for p=1:length(b)
    string{p,:} = {strcat(a,num2str(b(p)))};
end

string = 

    {1x1 cell}
    {1x1 cell}
    {1x1 cell}
    {1x1 cell}

Whereas, assigning the VariableNames directly:

T = array2table(ncoIED,'VariableNames',{'A' 'B' 'C' 'D'});

Works as intended.

This seems to be down to the way the strings are stored in the cell-array - each string is surrounded by ' ' whereas a = {'A' 'B' 'C' 'D'}; does not add this.

I need to be able to dynamically create string names by concatenating multiple variables - is there a way to do this that will be compatible with the VariableNames parameter?

For example, if I have two cell arrays and a numerical matrix, in these forms:

g =

TT

uID =

     3
     4
     5
    10

s =
    'CC'
    'NN'
    'AA'

I want to create 12 unique strings following these rules:

TT3CC
TT3NN
TT3AA
TT4CC
TT4NN
TT4AA
TT5CC
TT5NN
TT5AA
TT10CC
TT10NN
TT10AA

That can be used to label a table.

EDIT

Second set of naming rules:

TT3NN
TT4NN
TT5NN
TT10NN
TT3CC
TT4CC
TT5CC
TT10CC
TT3AA
TT4AA
TT5AA
TT10AA

obchardon · Accepted Answer · 2015-09-02 14:52:31Z

1

Something like:

    g   = 'TT';
    uID = [3 4 5 6];
    s   = {'CC' 'NN' 'AA'};

    for i = 1:length(uID)
        for j = 1:length(s)
           names{(i-1)*length(s)+j} = strcat(g,int2str(uID(i)),s{j});
        end
    end

or

inc = 1;
for i = 1:length(uID)
    for j = 1:length(s)
       names{inc} = strcat(g,int2str(uID(i)),s{j});
       inc = inc + 1;
    end
end

?

You just have to transform all your variables into string.

to extract a string from a cell you can write: mycell{i}.

finally strcat concatenate the 3 parameters.

EDIT

For your second request it start to be a little bit more tricky:

sets    = {[1:numel(uID)],[1:numel(s)]};
[p1 p2] = ndgrid(sets{:});
comb    = sortrows([p1(:) p2(:)],2); 

for i = 1:length(comb)
     names{i} = strcat(g,int2str(uID(comb(i,1))),s{comb(i,2)});
end

I generate all the possible combination with ndgrid then i sort the combination array according to the second row.

you just need to change your s cell:

s = {'NN' 'CC' 'AA'}

edited Sep 2, 2015 at 14:52

answered Sep 2, 2015 at 14:07

obchardon

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2 Comments

Adriaan Over a year ago

Please add an explanation what you're doing here as opposed to posting bare code.

AnnaSchumann Over a year ago

Works very well thank you. Could this be easily altered to produce the second naming pattern shown in the OP?

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