Merging two categorical columns using a rule

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Wendy Cameron 2018-5-11

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评论： Wendy Cameron 2018-5-12

Hi,

I am wanting to merge/add 2 categorical columns but need to use a rule.

For example a= [Flowering not not not], b=[not not not budburst] and I want the final output to be c=[Flowering not not Budburst]?

Basically, when merging/adding the two vectors, I want the word "flowering" or "budburst" to take precedence over "not". "Flowering" will never clash with "budburst" and "not "not" would give a "not".

Thanks, Wendy

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Answer 1

Ameer Hamza 2018-5-11

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编辑：Ameer Hamza 2018-5-11

在 MATLAB Online 中打开

Here is one way

% Extracting data from yor file
data = readtable('phenology.xls');
a = categorical(data.A);
b = categorical(data.B);
% preparing default output vector
c = categorical(repmat({'not'}, size(a)));
indA = ~ismember(a, 'not');
indB = ~ismember(b, 'not');
c(indA) = a(indA);
c(indB) = b(indB);
isequal(c, data.C)
ans =
  1 <--- The generated c is same as in your xls file.

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Answer 2

Greg 2018-5-11

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Make your categorical array ordinal (with "not" as the lowest value), then use c = max(a,b). This is only guaranteed to work since you said valid values won't conflict.

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Greg 2018-5-12

在 MATLAB Online 中打开

Have a read of the documentation page " Ordinal Categorical Arrays ."

Basically, you specify the valueset (allowable entries) in order of smallest to largest:

valueset = {'not';'Budburst';'Flowering'};
var = categorical(a,valueset,'ordinal');

Wendy Cameron 2018-5-12

Thank you, I've read that now and it seems to make even more sense the way you've written it here!.

Thank you very much. Wendy

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Answer 3

Wendy Cameron 2018-5-11

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phenology.xls

Hi,

I have attached some sample data. Basically I have columns A and B but want to get column C. I couldn't quite get the method above to work but I am very new to Matlab.

Thanks for your patience. Wendy

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Ameer Hamza 2018-5-11

I just tested my code with your data and it is giving correct output. Can you tell which line is creating the error? Refer to my edited answer to see how to read data from the xls file.

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Answer 4

Wendy Cameron 2018-5-11

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Yes that worked with the table I sent you as you describe. I get a 42 x 1 categorical - thank you very much. I'm now just trying to join that column into my original table. Join or interjoin might work.

Thanks, Wendy