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classify data from csv fil

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hello everyone
I want to read data from csv file and classify these data. my csv look like this:
0
0.139999945
0.209999918
12.86283386
0
-0.649996554
-2.609774285
-114.4151
...
its [154*1][row*col], I want to classify these data as
  • (if data = 0 then write 0 in the second column)
  • (if 0<data<=45 then print 1)
  • (if 45<data<=90 then print 2)
  • (if 0>data>=-45 then print 3)
  • (if -45>data>=-90 then print 4)
I don't know what should I write in the condition statement! the following is my attempt but it doesn't give the desired output.
M = csvread('imu.csv')
[rows cols] = size(M);
for k = 1:length(M)
if M == 0
A=0;
elseif 0<M<=45
A=1;
elseif 45<M<=90
A=2;
elseif 0>M>=-45
A=3;
else
A=4;
end
end
csvwrite('imu2.csv',A);

  1 Comment

Image Analyst
Image Analyst on 11 May 2018
"write 0 in the second column" of what , A or M? If A, then what is in the first column of A?

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Accepted Answer

Star Strider
Star Strider on 11 May 2018
The loop and if block are not necessary.
I would simply do this:
M = randn(10, 1); % Create Vector
M = [M zeros(size(M))]; % Preallocate
M(M(:,1) > 0,2) = 1;
M(M(:,1) < 0,2) = 2;
That initially creates the second column as zeros, then sets the second column according to the positive and negative values in the first column.

  4 Comments

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Star Strider
Star Strider on 11 May 2018
My pleasure.
The code changes to:
M = [M zeros(size(M))]; % Preallocate
M(( 0 < M(:,1)) & (M(:,1) <= 45 ) ,2) = 1;
M(( 45 < M(:,1)) & (M(:,1) <= 90 ) ,2) = 2;
M(( 0 > M(:,1)) & (M(:,1) >= -45 ) ,2) = 3;
M((-45 > M(:,1)) & (M(:,1) >= -90 ) ,2) = 4;
That does what you want. I kept the previous data name (here ‘M’) for consistency. You are of course free to change it.
Khadija Al Jabri
Khadija Al Jabri on 11 May 2018
it's work!
Thank you so much, I appreciate your help.
Star Strider
Star Strider on 11 May 2018
As always, my pleasure!

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