CODEWITHSUNDEEP
matlabindexingfind
AnnaSchumann
AnnaSchumann

Reputation: 1271

Multiple queries (OR statements) using find

Currently to perform multiple queries using find, I invoke each query individually separated by |

index = find(strcmp(data{:,{'type'}},'A') | strcmp(data{:,{'type'}},'B') | strcmp(data{:,{'type'}},'C') | strcmp(data{:,{'type'}},'D'));

To find all rows that where the field 'type' contains either A, B, C or D.

data is held in a table hence the usage of }.

Is there a more concise way of doing this without the need to specify the query in full each time?

Upvotes: 0

Views: 208

Answers (1)

Chris Taylor
Chris Taylor

Reputation: 47402

You could use ismember instead of multiple uses of strcmp.

index = find(ismember(data{:,{'type'}}, {'A','B','C','D'}));

An alternative (because ismember will probably be slower than multiple uses of strcmp) would be to factor out the repeated code -

x = data{:, {'type'}}; %# This isn't valid MATLAB but whatever...
index = find(strcmp(x,'A') | strcmp(x,'B') | strcmp(x,'C') | strcmp(x,'D'));

You could also use multiple lines for readability

x = data{:, {'type'}}; %# This isn't valid MATLAB but whatever...
index = find(strcmp(x,'A') ...
           | strcmp(x,'B') ...
           | strcmp(x,'C') ...
           | strcmp(x,'D'));

Upvotes: 1

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