Copying rows from a matrix that meet a condition into new matrices

I know this is a rookie question, but I am a rookie MATLAB user...

I have the following matrix:

32  734786.452997685  5.70000000000000  361
32  734786.452997685  5.70000000000000  367
1  734786.452997685  5.69500000000000  100
31  734786.453009259  5.69000000000000  175
31  734786.453009259  5.69000000000000  182

what i need to do is put the rows into different matrices according to the value in the first column. so one matrix that only has the '1' rows, one that only has the '31' rows, and one that has only the '32' rows.

this is bloomberg bid/ask/trade data. if anyone knows how to write the bloomberg function that returns the individual bid, ask, and trade data elements i'd gladly take that also.

suggestions?

Answer 1

[Walter Roberson]

Ufirst = unique(YourData(:,1));
nval = length(Ufirst);
SeparatedData = cell(nval,1);
for K = 1:nval
  SeparatedData{K} = YourData(YourData(:,1)==Ufirst(K),:);
end

Then SeparatedData{1}, SeparatedData{2} etc would be the matrices.

You might also wish to consider instead

sortrows(YourData)

as you might find that it is not necessary to extract the data into distinct matrices if it is grouped together.

In the longer term, depending what you are doing with the data, you may wish to use John D'Errico's File Exchange Contribution considator()

Answer 2

[Fangjun Jiang]

Use logical index.

d=[32  734786.452997685  5.70000000000000  361
32  734786.452997685  5.70000000000000  367
1  734786.452997685  5.69500000000000  100
31  734786.453009259  5.69000000000000  175
31  734786.453009259  5.69000000000000  182];

UniCol=unique(d(:,1));
N=numel(UniCol);
Out=cell(N,1);
for k=1:N
    index=d(:,1)==UniCol(k);
    Out{k}=d(index,:);
end

Answer 3

[Timothy Stark]

Thank you both for your help. I'm at least glad it wasn't a one line answer....