classify data from csv fil

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);

[Image Analyst]

"write 0 in the second column" of what , A or M? If A, then what is in the first column of A?

Answer 1

[Star Strider]

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.

[Khadija Al Jabri]

thank you so much for your replay. its work with your code but I need more class as I edit my question above, could you take a look please? and give me your suggestion!

[Star Strider]

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]

it's work!

Thank you so much, I appreciate your help.

[Star Strider]

As always, my pleasure!