How to convert categorical data to numeric in separate columns?

Question

Amy Rafferty 2020-8-10

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/577702-how-to-convert-categorical-data-to-numeric-in-separate-columns

评论： Adam Danz 2020-10-26

% Hi! I have a dataset 'data5' with a column 'Location' which contains values Asia, US and Africa.
% I'm wanting to convert it to 3 separate columns, one for each location, which contains a 1 if the row is from that location and 0 otherwise
% This is the function I have created:
function data = categorical_values(data, var)
    uniques = unique(var);
    for i = 1:length(uniques)
        values(:, i) = double(ismember(var, uniques(i)));
    end
    t = table;
    [rows, cols] = size(values);
    for i = 1:cols
        t1 = table(values(:, i));
        t1.Properties.VariableNames = uniques(i);
        t = [t t1];
    end
    data = [t data];
end
% And this is the code I have been running, in a file called prep.m:
new = categorical_values(data5, data5.Location);
new.Location = []; % delete the old Location column
% I have been getting this error:
Error using categorical_values (line 11)
The VariableNames property is a cell array of character vectors. To
assign multiple variable names, specify names in a string array or a cell
array of character vectors.
Error in prep (line 16)
new = categorical_values(data5, data5.Location);
% Can anyone help??????? Thanks!

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Answer 1

Adam Danz 2020-8-10

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/577702-how-to-convert-categorical-data-to-numeric-in-separate-columns#answer_477640

编辑：Adam Danz 2020-10-26

在 MATLAB Online 中打开

Here's a more efficient solution.

% Create demo data
location = categorical({'Asia','US','Asia','Africa','Africa','US','US','Asia'}');
unqCountries = unique(location(:)')
unqCountries = 1×3 categorical array
     Africa      Asia      US 
% Create matrix of 1s % 0s.
% Columns are identified by "unqCountries"
countryIdx = location(:) == unqCountries
countryIdx = 8x3 logical array
   0   1   0
   0   0   1
   0   1   0
   1   0   0
   1   0   0
   0   0   1
   0   0   1
   0   1   0
% If you want to turn it into a table
T = array2table(countryIdx, 'VariableNames', string(unqCountries))
T = 8x3 table
    Africa    Asia      US  
    ______    _____    _____

    false     true     false
    false     false    true 
    false     true     false
    true      false    false
    true      false    false
    false     false    true 
    false     false    true 
    false     true     false

The error you're getting is because you're assigning a categorical variable as a table variable name which must be a character array or string. Convert to string:

t1.Properties.VariableNames = string(unique(i));