How can I divide a timestamp into intervals

I have a file with time stamps from 1996 that I have loaded to a matrix. I want to add customized intervals of the day to each row as 'text' or as 'key' 1/2/3/4 etc based on following zoning (early morning 12 AM - 8 AM, morning 8 - 12, afternoon etc.)

How can I achieve this is Matlab?

Answer 1

[Star Strider]

This works:

% Create  Data
nw = now;
dn = nw + [0:48]'/24;                       % Column Vector Of Date Numbers

ds = [0 8:4:24]/24;                         % Day Segments
df = rem(dn,1);                             % Fractional Parts Of Date Numbers
for k1 = 1:size(dn,1)
    tc(k1,:) = find(df(k1)>ds, 1, 'last');  % Time Categories
end

It depends on the dates and times being converted into date numbers (with datenum) in column vector ‘dn’. Then it strips out the fractional part of the date numbers in ‘df’ and uses the loop to compare them to the vector of day segments (in vector ‘ds’) in the loop, and assigns each to the time category in column vector ‘tc’. The loop seems to be the easiest way to do it.

The input to the routine is the column vector of date numbers ‘dn’, and the output is the column vector of time categories ‘tc’.

[Vivek]

Thanks!

[Star Strider]

My pleasure!