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Extract Variable/column with variable name from table

Asked by yvesvincent abgrall on 16 Sep 2019
Latest activity Commented on by yvesvincent abgrall on 16 Sep 2019
Hello,
I don't know how to extract a column with its variable name from a Matlab table.
I want to extract columns and not have to rename them afterwards in order to recreate a similar table bbut with only the column I want.
I need to extract them one at the time and the data types are different from one column to another.
I've tried different ways and read the matlab documentation but haven't found any solution.
Could you please help me? :)

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2 Answers

Answer by Steven Lord
on 16 Sep 2019
Edited by Steven Lord
on 16 Sep 2019
 Accepted Answer

In what form do you want the extracted variables to be stored?
A = magic(4);
T = array2table(A) % Variable names A1 through A4
smallerTable1 = T(:, {'A2', 'A4'}) % Smaller table with only two variables
smallerTable2 = T(:, [2 4]) % Smaller table with only two variables
vector1 = T.A2 % Double array, no variable names
vector2 = T{:, {'A2'}} % Double array, no variable names
vector3 = T{:, 2} % Double array, no variable names
If you want to process each variable from your table in turn, but you want to perform the same operation on each, consider using varfun.

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Thank you!
this is what I was looking for:
smallerTable1 = T(:, {'A2', 'A4'})

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Answer by Bob Nbob
on 16 Sep 2019

I believe you can get this as a return.
T.Properties.VariableNames % T is the table variable
Additionally, because you're putting them into another table, if you just extract the specific columns you want the new table, and they will carry the variable names with them.
>> A = randi(100,10,4);
>> A = array2table(A);
>> A.Properties.VariableNames
ans =
1×4 cell array
{'A1'} {'A2'} {'A3'} {'A4'}
>> B = A(:,[2,4]);
>> B.Properties.VariableNames
ans =
1×2 cell array
{'A2'} {'A4'}

  2 Comments

Thank you for your answer Bob Nbob.
Using Properties.VariablesNames doesn't extract the data of the column.
I need to extract both the data and the variable name.
As I mentioned, if you are extracting the column data into another table then the variable name will follow with it. Just put the information into a table class variable, which can be done most easily by indexing the portion of the original table that you want into a clean variable.

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