Plotting certain columns from a .dat file

2011 9 20
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Greetings all,
It's been quite some time since I've used MATLAB, and embarrasingly I've been struggling with this all day. Needless to say I am a bit rusty! I have a data file that has 8 columns of data (and has headers at the top). Right now I'm trying to just plot column 2 of the data on the x-axis and plot the 4th and 8th columns as two line plots along the y-axis.
I imagine you use fopen and textscan, but there's so many to choose from. Maybe importdata?
Any help would be appreciated. Thanks!

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Fangjun Jiang
Fangjun Jiang 2011-9-20

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If your data file format is consistent, try
data=importdata('MyFile.data');
For plotting, if you have a matrix A, A(:,2) is all the data in the second column so you can do:
plot(A(:,2),A(:,4),'r',A(:,2),A(:,8),'b');

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Jesse
Jesse 2011-9-20
Fangjun, ok thanks, but how would you go about plotting certain columns of the file as stated in the above question?
Jesse
Jesse 2011-9-20
Fangjun, ok thanks, but how would you go about plotting certain columns of the file as stated in the above question?
Jesse
Jesse 2011-9-20
Fangjun, thanks again. However, I did what you said:
data = importdata('MyFile.dat');
plot(data(:,2),data(:,4),'r',data(:,2),data(:,8),'b');
But I receive
??? Index exceeds matrix dimensions.
Error in ==> Tester2 at 5
plot(data(:,2),data(:,4),'r',data(:,2),data(:,8),'b');
data is somehow a 1x1 struct, not a matrix. Should I try another function?
Fangjun Jiang
Fangjun Jiang 2011-9-21
data is a structure, type data in Command Window to see what it contains. You need to do A=data.data.
You've used MATLAB long time ago so maybe going through the "Getting Started" in MATLAB document is beneficial.
Jesse
Jesse 2011-9-21
Fangjun,
Ah yes! I forgot about the . operator to make the matrices agree!
Thanks - that worked!

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