# Assign NaN to specific rows(based on criteria) for multiple table variables

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Marcel345614 on 1 Feb 2022
Commented: Marcel345614 on 2 Feb 2022
I want to assign NaN to (time-)table rows that match a criteria (T.Var1~=1). I would like to do this for specific variables in the table.
T.Var2(T.Var1~=1)=NaN; % Note: My variables are not called Var1, Var2, ... but I simplified it here to these names ;-)
T.Var5(T.Var1~=1)=NaN;
%...
T.Var10(T.Var1~=1)=NaN;
%...
I would like to do this in a shorter code. Is this possible?
I look for something like this:
T.{'Var2','Var5', 'Var7', 'Var10'}(T.Var1~=1)=NaN;

Turlough Hughes on 1 Feb 2022
You can do that as follows:
% Firstly some sample data
T = array2timetable(randi(3,10,5),'Rowtimes',datetime() + seconds(0:9))
T = 10×5 timetable
Time Var1 Var2 Var3 Var4 Var5 ____________________ ____ ____ ____ ____ ____ 01-Feb-2022 16:14:43 2 2 1 1 1 01-Feb-2022 16:14:44 2 1 2 3 3 01-Feb-2022 16:14:45 3 2 2 2 3 01-Feb-2022 16:14:46 1 3 1 3 2 01-Feb-2022 16:14:47 1 3 2 2 3 01-Feb-2022 16:14:48 1 3 3 3 2 01-Feb-2022 16:14:49 3 3 1 1 1 01-Feb-2022 16:14:50 1 3 3 1 3 01-Feb-2022 16:14:51 2 2 1 1 3 01-Feb-2022 16:14:52 1 1 1 3 2
% You can do it using column numbers
T{T.Var1==1,[2 4]} = nan
T = 10×5 timetable
Time Var1 Var2 Var3 Var4 Var5 ____________________ ____ ____ ____ ____ ____ 01-Feb-2022 16:14:43 2 2 1 1 1 01-Feb-2022 16:14:44 2 1 2 3 3 01-Feb-2022 16:14:45 3 2 2 2 3 01-Feb-2022 16:14:46 1 NaN 1 NaN 2 01-Feb-2022 16:14:47 1 NaN 2 NaN 3 01-Feb-2022 16:14:48 1 NaN 3 NaN 2 01-Feb-2022 16:14:49 3 3 1 1 1 01-Feb-2022 16:14:50 1 NaN 3 NaN 3 01-Feb-2022 16:14:51 2 2 1 1 3 01-Feb-2022 16:14:52 1 NaN 1 NaN 2
% or using variable names
T{T.Var1==1,["Var3", "Var5"]} = nan
T = 10×5 timetable
Time Var1 Var2 Var3 Var4 Var5 ____________________ ____ ____ ____ ____ ____ 01-Feb-2022 16:14:43 2 2 1 1 1 01-Feb-2022 16:14:44 2 1 2 3 3 01-Feb-2022 16:14:45 3 2 2 2 3 01-Feb-2022 16:14:46 1 NaN NaN NaN NaN 01-Feb-2022 16:14:47 1 NaN NaN NaN NaN 01-Feb-2022 16:14:48 1 NaN NaN NaN NaN 01-Feb-2022 16:14:49 3 3 1 1 1 01-Feb-2022 16:14:50 1 NaN NaN NaN NaN 01-Feb-2022 16:14:51 2 2 1 1 3 01-Feb-2022 16:14:52 1 NaN NaN NaN NaN
##### 3 CommentsShow 1 older commentHide 1 older comment
Turlough Hughes on 1 Feb 2022
No problem. The single quotes are type char and the double quotes are type string. You can see why Var1Var3Var5 came up just by typing it into the command window:
idx = ['Var1' 'Var3' 'Var5']
idx = 'Var1Var3Var5'
whereas when you concatenate strings the result is different:
idx = ["Var1" "Var3" "Var5"]
idx = 1×3 string array
"Var1" "Var3" "Var5"
You could also use a cell array of char's to index by the variable names:
T = array2timetable(randi(3,10,5),'Rowtimes',datetime() + seconds(0:9));
T{T.Var1==1,{'Var3', 'Var5'}} = nan
T = 10×5 timetable
Time Var1 Var2 Var3 Var4 Var5 ____________________ ____ ____ ____ ____ ____ 01-Feb-2022 17:00:03 2 1 3 3 3 01-Feb-2022 17:00:04 2 3 1 2 1 01-Feb-2022 17:00:05 1 1 NaN 3 NaN 01-Feb-2022 17:00:06 3 1 3 2 2 01-Feb-2022 17:00:07 2 3 1 2 3 01-Feb-2022 17:00:08 2 1 1 2 1 01-Feb-2022 17:00:09 1 1 NaN 1 NaN 01-Feb-2022 17:00:10 1 3 NaN 3 NaN 01-Feb-2022 17:00:11 1 2 NaN 3 NaN 01-Feb-2022 17:00:12 1 1 NaN 1 NaN
Marcel345614 on 2 Feb 2022
Thanks a lot! Now I understand it.

Benjamin Thompson on 1 Feb 2022
If you are assigning from a scalar it seems you must do this column by column. Use an index vector to select which rows to assign:
T.Var1 = [1 2 3 4 1]'
T.Var2 = 2*ones(5,1)
T.Var3 = 5*ones(5,1)
T.Var4 = 10*ones(5,1)
I = T.Var1 ~= 1
T2.Var2(I) = NaN
T2.Var3(I) = NaN
T2.Var4(I) = NaN
See the MATLAB help article "Access Data in Tables" for more data reading and writing examples.
Marcel345614 on 1 Feb 2022

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