Why do I get different responses when I run a piece of inside a function or directly in the command window?

When I run the following piece of code (directly in the command window, for debugging purposes):

categories_hash = arrayfun(@(idx) string2hash(categories{idx}), 1:size(categories));

- it works

but when I invoke the function that contains it, I get the following error:

Cell contents reference from a non-cell array object.

Error in intellegite>@(idx)string2hash(categories{idx}) (line 22)
categories_hash = arrayfun(@(idx) string2hash(categories{idx}), 1:size(categories));

Error in intellegite (line 22)
categories_hash = arrayfun(@(idx) string2hash(categories{idx}), 1:size(categories));

[Walter Roberson]

Could you give us some sample data? Also are you passing categories into your routine intellegite or are you creating it there?

Is string2hash from https://www.mathworks.com/matlabcentral/fileexchange/27940-string2hash ?

[Fernando Fernandes]

Exactly. String2hash comes from that link.

Categories is a very long cell array. To have an idea of this data:

test = categories(1:4);
>> test

test = 

      'a'
      'abaixo'
      'aberta'
      'abertas'

Moreover, it is being created inside my intellegite, when I have that issue. But, when I paste each single line of intellegite in the command window, for debugging purposes, it works fine. In other words, when I run the following command in Matlab, instead invoking my routine:

>> categories_hash = arrayfun(@(idx) string2hash(categories{idx}), 1:size(categories));

it works.

[dpb]

Need to see the call and the error in context; probably the function definition line of the function intelligite as well.

Have you set a breakpoint inside the function and done your debugging in that context? I'll bet inside there you've dereferenced the cell array already somehow/somewhere in what's not shown here.

[Walter Roberson]

If you put a breakpoint at the beginning of that line inside the routine, let it run to there, and then copy and paste that to the command line, which output do you get?

[Fernando Fernandes]

I get this following output:

keywords = intellegite(lplain_text, dictionary);
22  categories_hash = arrayfun(@(idx) string2hash(categories{idx}), 1:size(categories));
K>> categories_hash = arrayfun(@(idx) string2hash(categories{idx}), 1:size(categories));
Cell contents reference from a non-cell array object.

Error in intellegite>@(idx)string2hash(categories{idx})

[Fernando Fernandes]

This is the routine code until this point:

function bag = intellegite(c_tokens, dictionary)

vec_cat = '';

for m = 1:length(c_tokens)

  for i = 1:length(c_tokens{m})

    vec_cat = [vec_cat ; c_tokens{m}(i)];

  end

end

categories_ = unique(vec_cat);
categories = categories_(2:length(categories_));

categories_hash = arrayfun(@(idx) string2hash(categories{idx}), 1:size(categories));

[Fernando Fernandes]

Guys, thanks for the help. With the debugging tool you have just taught me, I've found out where I was dereferencing it! ... It was in the caller function. Thank you!

[dpb]

Kewl~the debugger is most powerful tool, indeed.

Demonstrates that context is important; was sure to point of near certainty that was the problem. Matlab rarely is wrong in its error diagnosis of this type... :)

Answer 1

[Walter Roberson]

You have

vec_cat = '';

then you have a double-nested loop that will not necessarily execute the inner code at all (because the input could be empty.)

Then you unique() this item that might still be '', after which you try to use the result of that as if it were a cell array.

You should be initializing vec_cat = {};