Split array in 3 groups by using one column values

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Hi,
I would like to split my data in 3 groups based on the values in axis 1
x = < 25 i would like to get a 0
x = > 25 < 419 i would like to get a 1
x = > 419 i would like to get a 2
how can I do this?
% Clear memory
clear; close all;
% Load data
T=readtable('SC01001 (2018-11-23)15sec.csv','PreserveVariableNames',true)
x1=T(:,1); %Date
x2=T(:,2); % Time
y1=T(:,3); % Axis 1
if
y1 <25
y1 = 0
elseif
y1 25>y1<419
y1 = 1
elseif
y1 >419
y1 = 2
end

Accepted Answer

Marta G
Marta G on 24 Feb 2020
Edited: Marta G on 24 Feb 2020
You shouldnt use a vector in a if condition.
In your case, it would be more effective to use this
loc=find(y1<25);
y(loc)=0;
loc1=find(y1>25 & y1<419);
y(loc1)=1;
loc2=find(y1>419);
y(loc2)=2;
If you are new to matlab you might understand the problem better with a for loop.
for i=0:length(y1)
if(y1(i)<25)
y(i)=0;
elseif (y1(i)>25 & y1(i)<419)
y(i)=1;
else
y(i)=2;
end
end
I prefer to not rewrite any variable i am using until it is completely necessary.
Make sure you really need those intervals and consider what you have to do if y1=25 since in your original code it would not enter any if else condition
  7 Comments
Annick
Annick on 25 Feb 2020
Everything above the for loop works for me. This is the screen I get. Even when I try the xlsx file, i keep getting the same error message
Marta G
Marta G on 25 Feb 2020
Edited: Marta G on 25 Feb 2020
Hello,
Thank you Ankit for your correction
There is a step missing:
x1=T(:,1); %Date
x2=T(:,2); % Time
y1=table2array(T(:,3)); % Axis 1
for i=1:length(y1)
if(y1(i)<25)
y(i)=0;
elseif (y1(i)>25 & y1(i)<419)
y(i)=1;
else
y(i)=2;
end
end
Make sure in future problems that you read the error and understand what it means, as that line missing is easily solvable. If you need matrix or vectors instead of table you can use table2array: https://es.mathworks.com/matlabcentral/answers/380821-how-to-convert-table-to-matrix

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