Importing formated time data into matlab

Hi, I'm new to MatLab, but not completely new to programing, and I am ooking for a way to import data with a time stamp which formatted as hh:mm:ss AM/PM. Using the import wizard it doesn't recognise it as data but text. Is there a way of doing this or do I need to change the input file? Cheers, Karen

Answer 1

[Kevin Holst]

It all depends on what you're wanting to do with this data. You may be able to use the time just fine as a string. I'd suggest looking into using either datenum or datestr once the data is imported into matlab.

[Karen Hornsby]

Well I don't seem to be able to load the time data at all. Using the import wizard I can load the values recorded at each time but on the time itself. It's almost as though I can't load text and numeric data at the same time. I wan to load 1 array with the time as a string and the potentially convert it and a second array with the values. I'm sure you can do this but I'm at a loss as to how to interogate the help file to get a meaningful ans!

[Kevin Holst]

Could you provide me a sample couple of lines of the data you're attempting to import?

[Karen Hornsby]

sure

Date/Time Start: Thursday, February 09, 2012 11:54:22 AM

Title: Outdoor air test 2/9/12 compare to original FMPS

Comments:

Instrument Label: TSI Model 3091,Serial Number 71105053, Firmware Version MCU:3.11,DSP:3.02

Instrument Status: Normal Status.

Instrument Errors: No Errors Detected

Dilution Factor: 1.000

Concentration [#/cmｳ]

Channel Size [nm]: 6.04 6.98 8.06 9.31 10.8 12.4 14.3 16.5 19.1 22.1

Time

11:54:23 AM 150.692 160.423 313.266 609.222 762.272 772.416 779.164 782.516 722.794 600

11:54:24 AM 198.732 212.745 366.206 659.115 792.899 767.558 765.893 787.907 733.418 602.428

11:54:25 AM 190.677 201.242 363.418 677.203 834.797 836.2 833.33 826.187 747.499 597.266

11:54:26 AM 187.069 200.672 360.485 666.509 823.894 832.639 833.132 825.373 740.968 579.916

11:54:27 AM 170.977 171.95 331.503 649.637 820.455 843.956 833.809 790.015 695.145 549.201

11:54:28 AM 223.65 225.432 371.054 660.518 805.386 805.657 797.943 782.244 701.252 554.967

[Karen Hornsby]

I was loooking for a way to attache a text file but one did not present itself!

I'd rather not have to clip the meta data out completely as I have 2 identical intruments to analysis and they will be measuring at 2 differnt highs so I need to be able to keep them striaght in my head.

Answer 2

[Kevin Holst]

Ok, so it looks like you won't be able to use matlabs fancy, easy data importer with this file, but if you will always be getting data in this format, you can create your own import function.

My suggestion, and this won't be pretty but it'll get the job done, is to do something like this:

fid = fopen('data.txt');
dateTimeStart = textscan(fgetl(fid),'Date/Time Start:%s','Delimiter','\t');
title = textscan(fgetl(fid),'Title:%s','Delimiter','\t');
comments = textscan(fgetl(fid),'Comments:%s','Delimiter','\t');
instrumentLabel = textscan(fgetl(fid),'Instrument Label:%s','Delimiter','\t');
fgetl(fid)
% etc collecting the data you want to keep in variables and using plain fgetl(fid) commands to skip a blank line
% for the channel size line, I'd probably use fgetl to get the whole line
% as a string and then cut off the first x characters, leaving just the
% numbers, and then you could use str2num to get those values into an array

% then we get to the real data.
textscan(fid,'%s %s %f %f %f %f %f %f %f %f %f %f') % this scans in all of your data into a 1x12 cell array, the first two columns are the time and AM/PM, the rest are numbers.

hope that helps!

[Karen Hornsby]

Hi Kevin,

sorry it has taken me so long to look at this, one of the instruments has been playing up.

I have managed to pull out all the meta data in to variables, but the main body is proving tricky.

So I can separate the time from the rest of the data but the AM onwards all comes out together. I think this is because the values are comma serperated rather than space delimited. is there a way to change the delimiter part way through a row of data do you know?

[Kevin Holst]

Karen,

Sorry for the delay, I was on vaca :) Unfortunately I'm away from my computer with Matlab and am unable to try this suggestion, but have you tried something like:

textscan(fid,'%s %s %f %f %f %f %f %f %f %f %f %f','Delimiter',{' ',','})

[Karen Hornsby]

Hi Kevin,

I did try this, but no joy. However I was contacted by Matlab to help in a servey of sorts and they produced the following anwser to my throny time stamp issue.

dateTimeStart = textscan(fgetl(fid),'Date/Time Start:%s','Delimiter','\t')

dateString = dateTimeStart{1,1};% pulls data out of cell

formatString = '"dddd, mmmm dd, yyyy HH:MM:SS AM"'; % tells the datenum command what format the time stamp is in

dateTimeStart_datenum = datenum(dateString, formatString);

this works perfectly.

Thanks for all the help though :)

Answer 3

[Karam Jaradat]

I suggest you to import the dates to excel first and change the format of the dates column to general, then copy the content and save it in txt file, then import this file to Matlab, it should work!