# Help with Table and Row indexing

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Nina Perf on 14 May 2022
Edited: Voss on 14 May 2022
Hi,
I have the following table Predictions, where there are 2 Days, 2 different Time points, for 2 different Birds, 3 Tries per day.
I want to:
1. Check If the Row number is a True Positive (meaning the column True and Predicted have the same value)
2. Check If the Row number is a True Positive and the Predicted value is '1'. Save those Row numbers in a variable called RN.
3. From another table T with the same dimentions as the Predictions table, I only want to keep the Row numbers as assigned to RN.
Can you help?

Voss on 14 May 2022
Edited: Voss on 14 May 2022
Predictions = S.Predictions
Predictions = 22×6 table
Day Bird Time Try True Predicted ___ ____ ____ ___ ____ _________ 1 004 Pre 1 0 0 1 004 Pre 2 0 0 1 004 Pre 3 0 0 1 004 Post 1 0 0 1 004 Post 2 0 0 1 004 Post 3 0 0 1 006 Pre 1 1 1 1 006 Pre 2 1 1 1 006 Pre 3 1 1 1 006 Post 1 1 1 1 006 Post 2 1 1 2 004 Pre 1 0 0 2 004 Pre 2 0 0 2 004 Pre 3 1 0 2 004 Post 1 0 0 2 004 Post 2 0 0
isTruePositive = Predictions{:,'True'} == Predictions{:,'Predicted'};
isTruePositivePredicted1 = isTruePositive & Predictions{:,'Predicted'} == 1;
% here are the row numbers:
RN = find(isTruePositivePredicted1)
RN = 8×1
7 8 9 10 11 18 19 21
% Two different ways to keep only certain rows
% of the other table T:
% Option 1: use logical indexing, and discard
% rows of T that are not true positive where
% 1 was predicted (in this case you don't need RN):
T{~isTruePositivePredicted1,:} = [];
% Option 2: use row indices RN to keep those rows
% that are true positive where 1 was predicted:
T = T{RN,:};

R2021a

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