MATLAB: How to count how many x are greater than (x>0.2, 03 and 0.4) in a specific time

count

Hi Everybody,
I need to know how many (x>0.2,0.3&0.4)occurred at each hour. First, count it to make me able tabulate it (i.e. in time between 5-6, we observed 5 event(x>0.2) and so on) and then plot it as a bar. Please assume, x and y are defined as a column data in .xls format.
x             y
0.05          10 
0.1           10.1 (1 min)
0.02          10.2
0.2           10.3
0.012         10.4 
.             . 
.             . 
.             .
0.2           11
Thank you in advance,

Best Answer

The following could be a solution..
 >> x = rand(1,1e3)/2 ;             % Fake x, for the example. 
 >> y = sort(rand(1,1e3)*23.99) ;   % Fake y, for the example.
Build a cell array of distributions
 >> bins  = 0.05 : 0.1 : 0.45 ;              
 >> dists = arrayfun(@(h) hist(x(floor(y)==h), bins), 0:23, ...
                     'UniformOutput', false) ;
Test..
 >> size(dists)
 ans =
     1    24
 >> dists{1}                      % Distribution for the period [0-1h[.
 ans =
     6     6     9    12     6
 >> dists{12}                     % Distribution for the period [11-12h[.
 ans =
     3    12     4     7     5
so for the period [11-12h[, 3 values are in the range [0,0.1[, 12 in the range [0.1, 0.2[, etc..
Note: you can achieve the same thing using a more basic approach, that you would have to put in a loop..
 >> id_hr = y >= 11 & y < 12 ;    % Index of y values (hrs) in the range 11-12h.
 >> sum(x(id_hr) < 0.1)           % Count # of corresponding x values below 0.1.
 ans =
      3
here we find the 3 that we found above as 1st element of dists{12}.
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