How do I group a sample data by a column into small groups?

I have a sample dataset of the form below and I want to sort into group of A = 11 - 20, B = 21 - 30, C = 31 - 40, etc. using the second column to do the sorting. I tried this

N = sortrows(N,2);
if N(:,2)<=0; 
  N0 = N; 
elseif (N(:,2)>=1) & (N(:,2)<=10);
  N10 = N; 
elseif (N(:,2)>10) & (N(:,2)<=20);
  N20 = N;
elseif (N(:,2)>20) & (N(:,2)<=30);
  N30 = N;
elseif (N(:,2)>30) & (N(:,2)<=40);
  N40 = N;
if N(:,2) > 40
  N50 = N50(N);
end

but nothing was displayed

DATASET
16.07  88.9  1007
15.91  89.1  1007
19.87  67.48  1008
20.45  61.71  1008
21.62  53.97  1009
22.02  47.95  1009
18.54  82.9  1006
18.66  82  1006
18.46  84.1  1006
18.36  83.6  1006
24.38  54.33  1008
25.18  50.33  1008
25.9  46.73  1008
26.46  45.79  1008
30.29  31.58  1006
30.33  29.83  1006
31.76  24.36  1004
32.37  24.63  1004
32.38  26.74  1004
32.23  24.22  1004

Answer 1

[dpb]

>> edges=[-inf 1 10:10:40 inf];  % set up bin edges 
>> [n,bin]=histc(dat(:,2),edges) % count, bin...
>> for i=unique(bin).',dat(bin==i,2),end % display results
ans =
 29.8300
 24.3600
 24.6300
 26.7400
 24.2200
ans =
 31.5800
ans =
 88.9000
 89.1000
 67.4800
 61.7100
 53.9700
 47.9500
 82.9000
 82.0000
 84.1000
 83.6000
 54.3300
 50.3300
 46.7300
 45.7900

[Oluropo Dairo]

Thank you dpb.

However, I need the answers to include the other columns' corresponding value. Also, each of the answers in a separate file.

Many thanks and kind regards,

[dpb]

Purely demonstrative of the binning operation; do what you want with the data inside the loop...address whatever set/subset you wish; I just did the 2nd column for clarity that it did the binning as desired.

>> for i=unique(bin).',dat(bin==i,:),end
ans =
 1.0e+03 *
  0.0303    0.0298    1.0060
  0.0318    0.0244    1.0040
  0.0324    0.0246    1.0040
  0.0324    0.0267    1.0040
  0.0322    0.0242    1.0040
ans =
 1.0e+03 *
  0.0303    0.0316    1.0060
ans =
 1.0e+03 *
  0.0161    0.0889    1.0070
  0.0159    0.0891    1.0070
  0.0199    0.0675    1.0080
  0.0204    0.0617    1.0080
  0.0216    0.0540    1.0090
  0.0220    0.0480    1.0090
  0.0185    0.0829    1.0060
  0.0187    0.0820    1.0060
  0.0185    0.0841    1.0060
  0.0184    0.0836    1.0060
  0.0244    0.0543    1.0080
  0.0252    0.0503    1.0080
  0.0259    0.0467    1.0080
  0.0265    0.0458    1.0080
>>

[Oluropo Dairo]

Yes dpb. I need you to specify the subsets within the loop.

Many thanks.

[dpb]

They're there, one each loop shows up as ans. Put whatever work you need to do on each set within the loop at that point; since you don't give any further information what that should be is unknown to us. As shown above, there's the full subset; the only difference is in the indexing of the second dimension to address the full row (":") instead of ("2").

What more is there?

[Oluropo Dairo]

The specified subsets are A, B, C, etc. Hence each ans ought to be A, B, C, etc. because only the last ans is retrievable.

Many thanks.

[dpb]

As I said, put what you want inside the loop...

"...each ans ought to be A, B, C,..."

Do NOT do this...for reasons and alternatives see the FAQ How_can_I_create_variables_A1.2C_A2.2C....2CA10_in_a_loop?

j=0;  % initialize counter for cell array
for i=unique(bin).' 
  j=j+1;              % increment counter
  a{j}=dat(bin==i,:); % store this set
end

[Oluropo Dairo]

Thank you very much dpb! You are absolutely correct.