Organize Data Using Cell Array of Time stamps?

Hi, I am trying to write a program that finds a major change to a known temperature. The data provided to me is in the form of an excel spreadsheet that contains a month's worth of data. The spreadsheet has a column headings of TAG DATE T1. I need to separate this column of timestaps by day so that I can use the index to find organize the temeperatures by day.

The beginning starts like this

raw_data=importdata('filename');
time_stamps=(raw_data.textdata(2:end,10));
new_time=datestr(time_stamps)

I want to use some variety of the find function to look for specific phrases in each timestamp eg. (1/20/2009)

time_stamps is a 43885x1 cell with terms that look like this '1/20/2009 7:00'

new_time is a string that I thought would help but actually seems less helpful.

Any ideas? Thanks

Answer 1

[Iain]

index = find(strcmpi(desired_date,time_stamps));

[Nathan]

The asnwer using that is

index =

     Empty matrix: 0-by-1

I can use

strmatch({'1/20/2009'},time_stamps)

I think. But I would have to run each date through this. I could use a date matrix and a loop but the matrix doesn't come out right if I use a format like

[1/20/2009 1/21/2009....] or ['1/20/2009' '1/21/2009' ..... ]

[Iain]

For strcmpi to work, you need to ensure that the date you search for is an EXACT match to an entire string - this would, by necessity, include the time.

I would suggest that you consider changing the dates to serial date numbers via "datenum", you can then use

serials = datenum(time_stamps);

index = find(serials > datenum(desired_date),1)