MATLAB Central Newsreader - comparison of cell entries

comparison of cell entries

Corinna Schmitt — Wed, 08 Aug 2007 11:45:02 -0400

Hallo,

I have a cell construction with 9 columns where the
following data is stored:

1 1 1 1 1 AR_WIZ
165855.0 59748.0 01_01_01_01
1 1 1 1 0 AR_WIZ
139876.0 60372.0 01_01_01_01
71662.0
71760.0
71447.0
71760.0
69771.0
70356.0

Now I want to delete those rows where in column 9 nothing
stands. My idea was the following one:

x=finalTable;
test='';
for i=1:(numberOfRows-1)
    a=x(i,9)
    if test==a
        for j=1:9
            x(i,j)=[];
        end
    end
end

Here an example: If we look in row 1 a=01_01_01_01 so
nothing is to do. It is the same with row 2. If we now look
at line 3 a=''. Now the if-cas eis true and all entries in
x in row 3 should be set to [] which means that the row
will be deleted.

At the moment I receive the error message: ??? Undefined
function or method 'eq' for input arguments of type 'cell'.

All in all I want to downsize x in the way that the rows
where column 9 is empty will be deleted.

Can anyone help me?

Thanks, Corinna

Re: comparison of cell entries

Titus — Wed, 08 Aug 2007 12:00:42 -0400

Hi Corinna,

several comments: line 4 should be a=x{i,9}, to get the element (string),
because, as the error message tells you, a is a cell array again, if you use
().
Next: to compare strings, use strcmp instead of ==, and instead of test=''
use isempty. So we end up with

x=finalTable;
for i=1:(numberOfRows-1)
   a=x{i,9};
   if isempty(a)
       for j=1:9
           x{i,j}=[];
       end
   end
end

Now: instead of marking them, just fill an array with true and false to kill
those rows later:

x=finalTable;
toBeDeleted = false(numberOfRows,1);
for i=1:(numberOfRows-1)
   a=x{i,9};
   if isempty(a)
    toBeDeleted(i) = true;
   end
end

Why not vectorize? You can do this in one step using cellfun
toBeDeleted = [cellfun(@isempty, x(1:numberOfRows-1,9)); false];

The false at the end, because you don't want to remove the last line?

and now delete the rows:
x(toBeDeleted, :) = [];

Titus

"Corinna Schmitt" <csc@mathworks.com> schrieb im Newsbeitrag
news:f9cabu$k9r$1@fred.mathworks.com...
> Hallo,
>
> I have a cell construction with 9 columns where the
> following data is stored:
>
> 1 1 1 1 1 AR_WIZ
> 165855.0 59748.0 01_01_01_01
> 1 1 1 1 0 AR_WIZ
> 139876.0 60372.0 01_01_01_01
> 71662.0
> 71760.0
> 71447.0
> 71760.0
> 69771.0
> 70356.0
>
> Now I want to delete those rows where in column 9 nothing
> stands. My idea was the following one:
>
> x=finalTable;
> test='';
> for i=1:(numberOfRows-1)
> a=x(i,9)
> if test==a
> for j=1:9
> x(i,j)=[];
> end
> end
> end
>
> Here an example: If we look in row 1 a=01_01_01_01 so
> nothing is to do. It is the same with row 2. If we now look
> at line 3 a=''. Now the if-cas eis true and all entries in
> x in row 3 should be set to [] which means that the row
> will be deleted.
>
> At the moment I receive the error message: ??? Undefined
> function or method 'eq' for input arguments of type 'cell'.
>
> All in all I want to downsize x in the way that the rows
> where column 9 is empty will be deleted.
>
> Can anyone help me?
>
> Thanks, Corinna

Re: comparison of cell entries

Corinna Schmitt — Wed, 08 Aug 2007 12:10:53 -0400

Hallo,

> Now I want to delete those rows where in column 9 nothing
> stands. My idea was the following one:
>
> x=finalTable;
> test='';
> for i=1:(numberOfRows-1)
> a=x(i,9)
> if test==a
> for j=1:9
> x(i,j)=[];
> end
> end
> end
>

I just solved the first error with the following code:

x=finalTable;
test='';
for i=1:(numberOfRows-1)
    a=x(i,9);
    b=i;
    if strcmp(test,a)==1
        for j=1:9
            x{i,j}=[];
        end
    end
end

But when I now check the size of x with 'whos' is the same
as before. The wanted rows are not deleted they are just
empty. I now constructed a new variable y:

y=cell(1576,9)
for counter=1:1576
    y(counter,1)=x(counter,1);
    y(counter,2)=x(counter,2);
    y(counter,3)=x(counter,3);
    y(counter,4)=x(counter,4);
    y(counter,5)=x(counter,5);
    y(counter,6)=x(counter,6);
    y(counter,7)=x(counter,7);
    y(counter,8)=x(counter,8);
    y(counter,9)=x(counter,9);
end

y has now the size I wanted.

But is there no easier way for this step?

Thanks, Corinna

Re: comparison of cell entries

us — Wed, 08 Aug 2007 14:05:21 -0400

Corinna Schmitt:
<SNIP wants to remove the little guys...

> Now I want to delete those rows where in column 9 nothing
stands...

one of the many solutions

% some data
     c{1,1}=1:10;
     c{2,1}=1:5;
     c{3,1}=1:15;
     c{4,1}=1:20;
% the engine
     len=cellfun(@length,c);
     c(len<10)=[];
% the result
     c

us