Entering huge arrays of numbers...

I have a thermocouple problem I am working on. I am given a set of data that i need to enter into matlab before I can get started. The data I have is time and corresponding temperature. I can get the time into matlab because it is at set intervals, but the temperatures are sporadic. how do you input a very large set of data(10 pages) that has a start and ending value, but no specific increment? Any help would be greatly appreciated.

[per isakson]

"given a set of data that i need to enter into matlab" &nbsp Is that in the form of a text file? In that case what is the format? How do you want data organised in Matlab? Did you try the tool, Import Data under the HOME tab?

[Joseph]

I have time and corresponding temp. like below:

    Time  Temp
    .01   22.59708
    .02   22.61797
    .03   22.59888

 etc...

I need to plot the data in matlab but there are 10 pages worth. i want to plot temp vs time. it is currently on online file.

[per isakson]

I assume

• this is a snap-shot of the first few lines of a text file!
• you did not try the tool, Import Data under the HOME tab

Am I correct?

[Joseph]

correct

[John D'Errico]

So use textread, or any of a huge variety of tools. Whats the problem?

Answer 1

[John D'Errico]

Read it in from a file, as a list of (time, temperature) pairs. So it can be either a 2-d array with say two columns, or a pair of vectors. If the times span too long of a time, you will probably need datenum to convert them into a numeric time format.

If you have the data, surely you can get it into an simple text file, or even an Excel spreadsheet? Start typing.

Answer 2

[Star Strider]

I’d appreciate a bit more information. What do you mean by ‘the temperatures are sporadic’? Do you have constant sampling times but the temperatures are missing from some of them, or do the temperatures have a large amount of variability?

There may be several ways to deal with your data once we know a bit more about it. No guarantees though with what you’ve already told us.

[Joseph]

the times are in .01 increments. but the corresponding temp values do not increase uniformly. i have all the given times and corresponding temps, but it is too much data to enter manually. here is a small sample of what was given:

Time Temperature

0.01 22.72926

0.02 22.50903

0.03 22.75125

0.04 22.56175

0.05 22.69901

0.06 22.5808

[Star Strider]

Noise is normal in empirical measurements. That’s the reason statisticians get the big bucks.

How do you want to handle the variability? I would either just leave it alone, or if you have a mathematical model of how it should work, fit a linear or nonlinear regression curve to it. The model depends on the system you are measuring, the time-temperature curve you hypothesize, the thermocouple interface, and other technical issues.

It would be best if you also had a model of your thermocouple and could model the voltage and linearisation of it with respect to temperature, as well. That might help you get a comprehensive temperature-voltage model, but then thermocouple interfacing circuitry could have advanced to the point that such is not an issue since I last dealt with them.

[Joseph]

Thanks, but I really just need to get the data into matlab so i can plot it. Is there a way to get data from a file into matlab? it is an internet file

[Star Strider]

For an Internet file, there are several ways to read it. Unfortunately, these have also changed between MATLAB versions, so you may need to search the documentation for your version. The online documentation (for R2014b) is the collection of routines linked to in Web Access.

After you download it, reading it into your MATLAB workspace depends on the file format. That is another huge subject, so I refer you to the documentation for Data Import and Export.

It’s not as daunting as it seems. It becomes a lot simpler when you know more details about the file.

Answer 3

[per isakson]

This is the way I would do it

    fid = fopen( 'cssm.txt' );
    cac = textscan( fid, '%f%f', 'Headerlines', 1, 'CollectOutput', true );
    fclose( fid )
    num = cac{1};
    plot( num(:,1), num(:,2) )

where cssm.txt is in the current directory (if not use a full filespec ) and contains

    Time  Temp
    .01   22.59708
    .02   22.61797
    .03   22.59888