Error using == function when trying to group certain data

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MZINGAYE MUBAYA 2019-2-19

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https://ww2.mathworks.cn/matlabcentral/answers/445868-error-using-function-when-trying-to-group-certain-data

评论： MZINGAYE MUBAYA 2019-2-21

credit.csv

Im trying to run a code to create a subset of a group i.e females who are credit worthy but im struggling with getting program to recognize f for females

>> worthyf = credit(credit.gender=='f' & credit.Risk_class==1,:);

Undefined operator '==' for input arguments of type 'cell'.

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Answer 1

Jesus Sanchez 2019-2-19

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在 MATLAB Online 中打开

== only works for numbers. You are comparing strings and therefore you need to use "strcmp"

https://es.mathworks.com/help/matlab/ref/strcmp.html

An example in your code:

worthyf = credit(strcmp(credit.gender,'f') & credit.Risk_class==1,:);

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Guillaume 2019-2-20

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Actually, I completely forgot the most relevant class here, the newish string class. This has an overloaded == operator that is equivalent to strcmp. Unfortunately, that's going to lead to lot of confusion for beginner because indeed == doesn't work as they expect for char arrays (which unfortunately many people call strings) but does work for actual strings.

s = "somethingelse";   %an actual matlab string
if s == "something"
    disp('it''s something');
elseif s == "somethingelse"
    disp('it''something else');
end

works as expected

s = 'something else'
if  s == 'something'    %proper syntax: if strcmp(s, 'something')
    disp('it''s something');
elseif s == 'somethingelse'
    disp('it''something else');
end