MATLAB: How to extract data from a table based on a specific variable

#dataanalysis#dataextracttables

I have a huge csv file with 7 columns that I import into matlab as a table (see picture below).

Is there a way to split this table into smaller tables that contain all the rows with the same Asset Description? For example, I would like to create a table with all the rows where my Asset is 'Glendevon'. The different variables in the Asset Description Row are 210, which means that "manual" extract is not an option.

Thanks

Best Answer

Convert the categorical variables from character representation to categorical
Use findgroups and splitapply, grpstats, etc., to group by variable(s) value

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MATLAB: How to best scan a table for same element values and create arrays to store the extracted data successively

1) Do not create numbered variable names (names that you would have to generate dynamically), use the adequate container for your data, which is a cell array in your case.

2) You mention a table in your question's title but a file in the question's body. So what have you got?

3) I would read the file all at once in a cell array and then use unique and a loop to split the cell array into what you want:

fid = fopen('somefile.txt', 'rt');
allfiledata = textscan(fid, '%s %f %f'); %create a cell array with 3 columns
[var1, ~, locations] = unique(allfiledata{1});
subarrays = cell(1, numel(var1));
fullmatrix = cell2mat(allfiledata(2:end));
for varindex = 1:numel(var1)
  subarrays{varindex} = fullmatrix(locations == varindex, :);
end
celldisp(subarrays)

MATLAB: Search in tables.

Hi Manuel,

Based on your data and requirement, I came up with a code snippet that might be applicable. Try it out and let me know if it helps.

clear 
clc
%%Creating the two tables
EjemploElementos1=categorical({'2 400 E';'B VT 080'; '3 200 B';'EB WT 052';'Cali B';'Cali EE'});
catnames1={'M1';'M2';'M3';'M4';'M5'};
catnames2={'B';'E';'EE';'EB'};
EjemploElementos2=categorical([1 1 2 3 5 4]',1:5,catnames1);
EjemploElementos=table(EjemploElementos1,EjemploElementos2)
A=reshape(repmat(1:5,[4 1]),[],1);
EjemploMaq1=categorical(A,1:5,catnames1);
B=reshape(repmat(1:4,[5 1])',[],1);
EjemploMaq2=categorical(B,1:4,catnames2);
EjemploMaq3=rand([20 1]);
EjemploMaq=table(EjemploMaq1,EjemploMaq2,EjemploMaq3)
%%Searching through the table
searchCategories=categories(EjemploMaq.EjemploMaq2);
for i=1:size(EjemploElementos,1)
    for j=1:size(searchCategories,1)
        if strfind(char(EjemploElementos1(i)),searchCategories{j})
            TempColumn{i}=searchCategories{j};
        end
    end
end
TempColumn=table(categorical(TempColumn'));
EjemploElementos=[EjemploElementos TempColumn];
EjemploElementos.Properties.VariableNames{2} = 'EjemploMaq1';
EjemploElementos.Properties.VariableNames{3} = 'EjemploMaq2'; % Change the name of the temporary column that you created
C=join(EjemploElementos,EjemploMaq)
C(:,3)=[] % Remove the temporary column that you created

I hope this helps. You could neglect the first section of the code snippet (that basically generates the table) and replace it with your table data.

Regards,

Vidya Viswanathan

Best Answer

Related Solutions

MATLAB: How to best scan a table for same element values and create arrays to store the extracted data successively

MATLAB: Search in tables.

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