Delete rows from string array with just one value

Hi,

I have a string array like this:

x=[Na,Mg,Si ; V ; Na,Mg,Si,S ; Si ; Na,Mg,Al,P]

I want to delete all the rows which contain just one Value. Does somebody has an idea how it could work? Because I reached my limit of knowledge (really new in matlab).

I appreciate any idea :-)

[Henry Barth]

are Na,Mg,Si string variables?

[Tatjana Mü]

Yes, the string array just contains Elements as string variables. The problem is that they change from sample to sample, depends on the sample. Sometimes the elements stands alone in a row, but also in rows with other elements, so I cant just delete the elementname. I need a solution to general delete rows with just one value. I hope you understand what I mean.

Answer 1

[Arif Hoq]

as i don't have your data so i have added NaN string to make the same dimension cell array

x={'Na','Mg','Si'  NaN; 'V' NaN NaN NaN; 'Na','Mg','Si','S' ; 'Si' NaN NaN NaN; 'Na','Mg','Al','P'};
a=string(x);
y=rmmissing(a,1,'MinNumMissing',2);
output=cellstr(y)

output = 3×4 cell array
    {'Na'}    {'Mg'}    {'Si'}    {0×0 char}
    {'Na'}    {'Mg'}    {'Si'}    {'S'     }
    {'Na'}    {'Mg'}    {'Al'}    {'P'     }

[Arif Hoq]

Or if you cell array looks different

x={{'Na','Mg','Si'};{'V'};{'Na','Mg','Si','S'};{'Si'};{'Na','Mg','Al','P'}}

x = 5×1 cell array
    {1×3 cell}
    {1×1 cell}
    {1×4 cell}
    {1×1 cell}
    {1×4 cell}

for i=1:size(x,1)
if numel(x{i,:})==1
    x{i,:}=[];
end
end
output=x(~cellfun('isempty',x))

output = 3×1 cell array
    {1×3 cell}
    {1×4 cell}
    {1×4 cell}

[Tatjana Mü]

Sadly, it doesnt work, because the size of the array varies :-/ I attached my resultfile. For example the first row is just Na and should be deleted. But every resultfile is different in size

[Tatjana Mü]

@Arif Hoq your idea is really good. I tried it with my data. My string array is called "intens_RL_final".

for t=1:size(intens_RL_final,1)
    if numel (intens_RL_final{t,:})==1
        intens_RL_final{t,:}=[];
    end
end
intens_RL_final=intens_RL_final(~cellfun('isempty',intens_RL_final));

I attached you the result. Every element is now in one column. I don't find my mistake.

[Arif Hoq]

it should work like that.

[Tatjana Mü]

@Arif Hoq Sorry I dont understand the last line. So first you search for lines which have the size 1 and delete them? Do I understand correct, that you use the cellfun line for deleting lines which are empty? Why do you use "~" in front of the cellfun function?

[Henry Barth]

~ means NOT in matlab. If you take a closer look at this line of code:

intens_RL_final = intens_RL_final(~cellfun(@isempty,intens_RL_final));

cellfun(@isempty,intens_RL_final);

takes the handle to the isempty-function and your cell array of strings, loops over the cells and applies the function to every cell. Pretty much like this:

isCellEmpty = false(size(intens_RL_final));
for nCell = 1:numel(intens_RL_final)
    isCellEmpty(nCell) = isempty(intens_RL_final{nCell});
end

but in a slightly slower but more comfortable way. If we take a cell array as an example:

intens_RL_final = {{"Na","Mg","Si"};{[]};{"Na","Mg","Si","S"};{[]};{"Na","Mg","Al","P"}};

The logical output of this ( [false, true, false, true, false]) is then negated to ([true, false, true, false, true]). If this vector is applied to the cell array, every cell which has a corresponding true-element gets returned. Please be careful with char, string and cell data types. They are different and I still remember that it took a while for me to understand. The official matlab help sites are good when it comes to data types, I would recommend a read.

P.S.: The cellfun function, whilst having its drawbacks, is pretty powerful:

intens_RL_final = intens_RL_final(cellfun(@(cellIn) numel(cellIn)~=1,intens_RL_final));

This is one of the possible one-liners using cellfun that replaces your whole loop as well as the last line whilst only being barely readable ^^

[Arif Hoq]

~ supposed to mean not.

~= menas not equal.

isequal function returns empty cell. so ~ which is used before isempty fucntion returns not empty cell

[Henry Barth]

Isn't that what I said? Please correct me if I'm wrong!