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Re: log log scale scatterplot [message #94908 is a reply to message #94907]

Tue, 05 December 2017 13:34

benjamin.castellani is currently offline

benjamin.castellani
Messages: 7
Registered: October 2017

Junior Member

On Tuesday, December 5, 2017 at 11:21:27 AM UTC-7, sid wrote:
> Hello all,
> I need to plot in log log scale and it is a scatter plot and I need to get the slope and intercept after fitting with linfit. This needs to be plotted in logarithmic space. And also the correlation coefficient needs to be calculated in log-log space.
>
> I have 10 x values and 10 y values
> is this correct plot, alog10(x), alog10(y)
> or like this plot, x,y,/xlog,/ylog but I need the values in order to find the linfit.
>
> how to do this
> thanks

Here is a sample code that does what you need it to do:

;example data (5 points)
x = [1487,500,24,3455,2233]
y = [11,50,2400,32.3,111]

fit = linfit(alog(x),alog(y))
xfit=[0:max(alog(x)):max(alog(x))/100.]
yfit = xfit*fit[1]+fit[0]

p = plot(alog(x),alog(y),layout=[2,1,1],symbol='o',linestyle=6,c olor='blue')
p2 = plot(xfit,yfit,/overplot)

NOTE: You can use either of your plot techniques. This will just change the actual labels on the axes. One will be just the log powers (it will show 3 for 1000), the other will be the data values in log form (it will show 10^3 for 1000)

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[Message index]

		log log scale scatterplot By: gunvicsin11 on Tue, 05 December 2017 10:21
		Re: log log scale scatterplot By: benjamin.castellani on Tue, 05 December 2017 13:34
		Re: log log scale scatterplot By: benjamin.castellani on Tue, 05 December 2017 13:49
		Re: log log scale scatterplot By: gunvicsin11 on Wed, 06 December 2017 22:42

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