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MathGroup Archive 1998

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Re: ListPlot and List problem



Lars Freund wrote:
> 
> Hi,
> 
> I want to plot data that is stored in a file having in the format:
> 
> <frequence> <phase> <amplification>
> 
> and want to plot the BODE-Diagram. So I did:
> 
> myData = ReadList["filename",{Number, Number, Number}];
> 
> and now want a plot from <phase> over <frequence> and <amplification>
> over <frequence>I tried things like
> 
> ListPlot[Transpose[testData][[3]],PlotJoined->True]
> 
> but I always got the wrong list-format. I need
> 
> {freqence1,phase1},{freqence2, phase2}...
> 
> and I always get things like
> 
> {phase1, phase2, phase3} or so.
> 
> Can anybody help me a bit?
> 
> Thanks,
> 
> Lars

If the list that you get from ReadList is

In[1]:=
myData= {{f[i], p[1], a[1]}, {f[i], p[2], a[2]}, {f[i], p[3], a[3]}, 
  {f[i], p[4], a[4]}};


Then we can get

In[2]:=
#[[{1,2}]]&/@myData

Out[2]=
{{f[i], p[1]}, {f[i], p[2]}, {f[i], p[3]}, {f[i], p[4]}}

In[3]:=
#[[{1,3}]]&/@myData

Out[3]=
{{f[i], a[1]}, {f[i], a[2]}, {f[i], a[3]}, {f[i], a[4]}}

-- 
Allan Hayes
Training and Consulting
Leicester, UK
hay@haystack.demon.co.uk
http://www.haystack.demon.co.uk
voice: +44 (0)116 271 4198
fax: +44 (0)116 271 8642




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