MATLAB: How to Delete Non-Numeric Columns from Table

MATLABtable

I'm using readtable to load data from a text file. Some columns have text in them; others don't. I want to effectively delete the columns that have at least one entry of non-numeric data, so that I can convert the remaining table to an array (using table2array).

How can I do this?

Best Answer

I think it is better to use the “Import Data” tool which allows you to import data as an array directly using a GUI and also to generate scripts for doing the same everytime.

http://www.mathworks.com/help/releases/R2014a/matlab/import_export/import-data-interactively.html

However to answer your question the following steps and example should be helpful.

Create a TEXT file called “sampledata.txt” and copy the following data into it.

LastName,Gender,Age,Height,Weight,Smoker Smith,M,38,71,176,1 Johnson,M,43,69,163,0 Williams,F,38,64,131,0 Jones,F,S,67,133,0 Brown,F,49,64,119,0

Run the below script to delete the columns which have text in them and generate the required array. Note that if even one item in a column is a string then the whole column is of cell array

% read the data into  a variable
T = readtable('sampledata.txt')
V = T.Properties.VariableNames;
for i = [1:width(T)]
    v_is_cell(i) = iscell(T.(V{i}));
end
%use logical indexing to delete the required columns
T(:,v_is_cell) = [];
table2array(T)

T =

     LastName     Gender    Age     Height    Weight    Smoker
    __________    ______    ____    ______    ______    ______
    'Smith'       'M'       '38'    71        176       1     
    'Johnson'     'M'       '43'    69        163       0     
    'Williams'    'F'       '38'    64        131       0     
    'Jones'       'F'       'S'     67        133       0     
    'Brown'       'F'       '49'    64        119       0

ans =

    71   176     1
    69   163     0
    64   131     0
    67   133     0
    64   119     0

Related Solutions

MATLAB: Table row not selecting

You need to define LastName. How should your program know what it is? It's not a built in function or anything.

MATLAB: Sorting a table with strings and numbers

Use readtable() to read in the workbook

T = readtable(fullXlsFileName);

Then use sortrows() to sort the table based on the column with strings in it. Let's say that the column with strings is the first column, like in the example below. Then you'd just do:

LastName = {'Smith';'Johnson';'Williams';'Jones';'Brown'};
Age = [38;43;38;40;49];
Height = [71;69;64;67;64];
Weight = [176;163;131;133;119];
BloodPressure = [124 93; 109 77; 125 83; 117 75; 122 80];
% Create a table, T, as a container for the workspace variables.
T = table(LastName, Age,Height,Weight,BloodPressure)
% Sort rows by last name.
sortedTable = sortrows(T, 1)

In the command window, you'll see the unsorted table first, followed by the sorted table:

T = 
     LastName     Age    Height    Weight    BloodPressure
    __________    ___    ______    ______    _____________
    'Smith'       38     71        176       124     93   
    'Johnson'     43     69        163       109     77   
    'Williams'    38     64        131       125     83   
    'Jones'       40     67        133       117     75   
    'Brown'       49     64        119       122     80   
sortedTable = 
     LastName     Age    Height    Weight    BloodPressure
    __________    ___    ______    ______    _____________
    'Brown'       49     64        119       122     80   
    'Johnson'     43     69        163       109     77   
    'Jones'       40     67        133       117     75   
    'Smith'       38     71        176       124     93   
    'Williams'    38     64        131       125     83

Best Answer

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