Remove rows by time with datenum

Hi.I have a mx15 matrix. In column 1 are datenum values (datenum(Y,M,D,H,MN,S)). I want to remove rows if the time is earlier than 11:00 or later than 14:00. How would one do that ?

Answer 1

[dbmn]

assuming that A is your matrix with A(:,1) the column of your datenums, then simply do

% Determine which rows to delete
% (note that the "hours" of datenum are behind the decimal point)
% hence we do mod 1 to just get that number  
  rows_to_delete = mod(A(:,1),1)<11/24 | mod(A(:,1),1)>14/24;
% Delete them
  A(rows_to_delete, :) = [];

Or if you are using a newer version of matlab you could get to some extra comfort and use datetime

% Convert to datetime
  new_time = datetime(A(:,1), 'ConvertFrom', 'datenum');
% Determine which rows to delete  
  rows_to_delete = hour(new_time)<11 | hour(new_time)>14;
% Delete them
  A(rows_to_delete, :) = [];