MATLAB: How to make a logical array by comparing two date vectors

cell arraydatenumdateveclogical indexingmatching

Hello, could you please help me on the following issue. I imported an Excel file containing the vector of dates (44 by 1, type – cell):
[temp, holidays]=xlsread('Holidays.xlsx', 'Tabelle1', 'A1:A44').
Then, I created the date vector with a step of 1 minute:
start_date = datenum('18-Apr-2015 16:30:00');
end_date = datenum('19-Apr-2015 10:00:00');
interval = 10/24/60;
date = datestr(start_date:interval:end_date);
My goal is to create a logical array that puts 1 if the date from the second (longer) vector equals the date in the first vector and 0 otherwise.
I tried the code below, but I have problems with data formats, which I cannot solve. Error using datenum (line 179) DATENUM failed.
Caused by: Error using dtstr2dtnummx Failed on converting date string to date number.
criteria=[];
for i=1:length(date)
    if day(holidays(i))==day(date(i)) && month(holidays(i))==month(date(i)) && year(holidays(i))==year(date(i))
        criteria(i)=1
    else
        criteria(i)=0
    end
end
Can please anyone help on that? Thanks a lot in advance!

Best Answer

You could use ismember with the 'rows' option. It only takes two steps
  1. convert all of the dates into datevectors (not datenumbers) using datevec.
  2. call ismember on the first three columns of those dates (or pick whatever units you want to compare).
The output will be your desired logical vector.
Here is a full working example:
% all dates:
beg_date = datenum('18-Apr-2015 16:30:00');
end_date = datenum('19-Apr-2015 10:00:00');
interval = 10/24/60;
dat_mat = datevec(beg_date:interval:end_date);
% fake data:
holidays = {'18-Apr-2015 16:50:00';'19-Apr-2015 09:50:00'};
hol_mat = datevec(holidays)
% number of columns of the datevectors to compare:
N = 5;
idx = ismember(dat_mat(:,1:N),hol_mat(:,1:N),'rows');
and the output is a logical vector, exactly as requested. For this example it is true here:
>> find(idx)
ans =
     3
   105
This method has the advantage that you can very simply change the units that are being compared (by changing N), without needing to change any format strings.
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