Hi all, I was wondering if there was a 'simple' way to get IDL to plot a best fit l= ine for a sinusoidally-varying data set. For example, say temperatures were= recorded each hour for 5 days at a certain location, with each measurement= having an error of 2 deg C. Then we would have something like: day =3D findgen(121)/24 temp =3D 15 + 10*sin(10*!pi*findgen(121)/120) + 5*randomu(seed, 121) error =3D fltarr(121)+2 Is it possible from these three arrays for IDL to work out and plot a best = fit line? I have searched online, and can't really find what I'm looking fo= r. (surprisingly I have never had to plot a best fit line to anything befor= e!) Cheers, Liam

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9/30/2015 2:22:57 PM

liam.steele@gmx.co.uk writes: > I was wondering if there was a 'simple' way to get IDL to plot a best fit line for a sinusoidally-varying data set. For example, say temperatures were recorded each hour for 5 days at a certain location, with each measurement having an error of 2 deg C. Then we would have something like: > > day = findgen(121)/24 > temp = 15 + 10*sin(10*!pi*findgen(121)/120) + 5*randomu(seed, 121) > error = fltarr(121)+2 > > Is it possible from these three arrays for IDL to work out and plot a best fit line? I have searched online, and can't really find what I'm looking for. (surprisingly I have never had to plot a best fit line to anything before!) You will do well to start here: http://cow.physics.wisc.edu/~craigm/idl/fitting.html Cheers, David -- David Fanning, Ph.D. Fanning Software Consulting, Inc. Coyote's Guide to IDL Programming: http://www.idlcoyote.com/ Sepore ma de ni thue. ("Perhaps thou speakest truth.")

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9/30/2015 2:37:45 PM

On Wednesday, 30 September 2015 15:37:47 UTC+1, David Fanning wrote: > liam.steele@gmx.co.uk writes:=20 >=20 > > I was wondering if there was a 'simple' way to get IDL to plot a best f= it line for a sinusoidally-varying data set. For example, say temperatures = were recorded each hour for 5 days at a certain location, with each measure= ment having an error of 2 deg C. Then we would have something like: > >=20 > > day =3D findgen(121)/24 > > temp =3D 15 + 10*sin(10*!pi*findgen(121)/120) + 5*randomu(seed, 121) > > error =3D fltarr(121)+2 > >=20 > > Is it possible from these three arrays for IDL to work out and plot a b= est fit line? I have searched online, and can't really find what I'm lookin= g for. (surprisingly I have never had to plot a best fit line to anything b= efore!) >=20 > You will do well to start here: >=20 > http://cow.physics.wisc.edu/~craigm/idl/fitting.html >=20 > Cheers, >=20 > David > --=20 > David Fanning, Ph.D. > Fanning Software Consulting, Inc. > Coyote's Guide to IDL Programming: http://www.idlcoyote.com/ > Sepore ma de ni thue. ("Perhaps thou speakest truth.") Aha! That looks far more useful than anything I found. Thanks very much.

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9/30/2015 2:51:31 PM

On Wednesday, September 30, 2015 at 8:51:33 AM UTC-6, liam....@gmx.co.uk wr= ote: > On Wednesday, 30 September 2015 15:37:47 UTC+1, David Fanning wrote: > > liam.steele@gmx.co.uk writes:=20 > >=20 > > > I was wondering if there was a 'simple' way to get IDL to plot a best= fit line for a sinusoidally-varying data set. For example, say temperature= s were recorded each hour for 5 days at a certain location, with each measu= rement having an error of 2 deg C. Then we would have something like: > > >=20 > > > day =3D findgen(121)/24 > > > temp =3D 15 + 10*sin(10*!pi*findgen(121)/120) + 5*randomu(seed, 121) > > > error =3D fltarr(121)+2 > > >=20 > > > Is it possible from these three arrays for IDL to work out and plot a= best fit line? I have searched online, and can't really find what I'm look= ing for. (surprisingly I have never had to plot a best fit line to anything= before!) > >=20 > > You will do well to start here: > >=20 > > http://cow.physics.wisc.edu/~craigm/idl/fitting.html > >=20 > > Cheers, > >=20 > > David > > --=20 > > David Fanning, Ph.D. > > Fanning Software Consulting, Inc. > > Coyote's Guide to IDL Programming: http://www.idlcoyote.com/ > > Sepore ma de ni thue. ("Perhaps thou speakest truth.") >=20 > Aha! That looks far more useful than anything I found. Thanks very much. Hi Liam, Once you've done your fit, you can do an error bar plot like this: day =3D dindgen(121)/24 temp =3D 15 + 10*sin(10*!pi*findgen(121)/120) + 5*randomu(seed, 121) error =3D fltarr(121)+2 p =3D errorplot(day, temp, error, linestyle=3D'none') yfit =3D ... p1 =3D plot(day, yfit, '2', /overplot) Cheers, Chris

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9/30/2015 3:19:43 PM

On Wednesday, 30 September 2015 15:23:01 UTC+1, liam....@gmx.co.uk wrote: > Hi all, >=20 > I was wondering if there was a 'simple' way to get IDL to plot a best fit= line for a sinusoidally-varying data set. For example, say temperatures we= re recorded each hour for 5 days at a certain location, with each measureme= nt having an error of 2 deg C. Then we would have something like: >=20 > day =3D findgen(121)/24 > temp =3D 15 + 10*sin(10*!pi*findgen(121)/120) + 5*randomu(seed, 121) > error =3D fltarr(121)+2 >=20 > Is it possible from these three arrays for IDL to work out and plot a bes= t fit line? I have searched online, and can't really find what I'm looking = for. (surprisingly I have never had to plot a best fit line to anything bef= ore!) >=20 > Cheers, >=20 > Liam Thanks for the tips everyone. I've managed to get something which I think l= ooks correct, so that's good! I'll add the error bar plot when I work on th= e real data. The code I used was this: day =3D findgen(121)/24 temp =3D 15 + 10*sin(10*!pi*findgen(121)/120)+5*randomu(seed, 121) error =3D fltarr(121)+2 meanval =3D mean(temp) expr =3D 'P[0] + P[1]*sin(P[2]*2*!pi*findgen(P[3])/(P[3]-1) + P[4])' start =3D [meanval, (max(temp)-min(temp))/2, 5., 121, 0.] result =3D MPFITEXPR(expr, day, temp, error, start) fitline =3D result[0] + result[1]*sin(result[2]*2*!pi*findgen(result[3])/(r= esult[3]-1) + result[4]) plot, day, temp, psym=3Dsym(2) oplot, day, fitline

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9/30/2015 4:07:24 PM

Hi, I am new to using GNUPLOT and am trying to find the best fit line (to determine the slope) of a line that follows Power Law (is an exponential line). I realize I have to use a function f(x) = a*b**x. But, I do not know what to do next. Any help in this matter would be greatly appreciated. Thanks, Divya Divya Rao <divyarao09@yahoo.com> wrote: > Hi, > I am new to using GNUPLOT and am trying to find the best fit line (to > determine the slope) of a line that follows Power Law (is an > exponential line). First, a terminology issue: an exponential curv...

I am new to python so apologies for the ignorance with this question. How would I apply a line of best fit to a plot? My data are netCDF4 data files and this is essentially what I have done so far: swh1=netCDF4.Dataset('filename','r') hs1=swh1.variables['hs'] swh2=netCDF4.Dataset('filename'.'r') hs2=swh2.variables['hs'] plt.plot(hs1,hs2,'.') Cheers, Jamie --001a113a6020e6901104f5e5a9f1 Content-Type: text/plain; charset=UTF-8 None of these are in the standard library but why re-invent the wheel? Using numpy:...

Hi. Is there a function to calculate/plot the best fit line given a few (approx 3) points? I don't have any toolboxes, nor can I afford any. Can any function in the basic matlab application do this? Thanks! "Amir " <amirschricker.DELETE@DELETE.gmail.DELETE.com> wrote in message <g4o8va$aa7$1@fred.mathworks.com>... > Hi. Is there a function to calculate/plot the best fit line > given a few (approx 3) points? I don't have any toolboxes, > nor can I afford any. > > Can any function in the basic matlab application do this? Yes. help polyfit J...

I'm a total newbie at this guys. I have the following data in an .m file: x = 0:2:20; y = [0.02 0.26 0.35 0.53 0.66 0.78 0.88 0.96 1.03 1.06 1.14]; plot(x,y,'rx'); How would i fit a line of best fit to this graph? I know this is rudimentary stuff but as i said i'm a total newbie!!! Cheers for any help help polyfit /Johan Jamie Sutton wrote: > I'm a total newbie at this guys. > I have the following data in an .m file: > > x = 0:2:20; > y = [0.02 0.26 0.35 0.53 0.66 0.78 0.88 0.96 1.03 1.06 1.14]; > plot(x,y,'rx'); > > How would i fit...

Hello, I have a problem that is puzzling me for very long.I got this problem of fitting in 80 over text files and within each txt file,it contains about 120 datas.I want to from these datas generate a best fit line to cut through all these points.The program I am now using is Matlab.Please help and reply asap,as I need the info urgently. Thanks. In article <a488ubsdofj7@legacy>, kellyblue19@yahoo.com (Eid) writes: >Hello, > I have a problem that is puzzling me for very long.I got this >problem of fitting in 80 over text files and within each t...

Good afternoon, I am having trouble trying to figure out how to fit a nonlinear best fit line to my data in SAS. Any help would be greatly appreciated. Regards, Ligia ...

Hi everyone., The following code reads an image, allows user to select an ROI and then the intention is to select 1000 points randomly in the ROI and generate a best fit line through these points. By inserting breakpoints i see that the points generated randomly lie in the range of points belonging to the ROI. So, it seems there is no problem at this stage.I am not able to identify where else there is an error. Pls help. Thanx in advance. clc; close all; clear all; %WHEN USING THE IMAGE MAKE SURE THAT BW AND BW1 DO NOY HAVE TOO MANY ELEMENTS, IF THEY DO CROP BW AND BWI AND USE THE CROPPED...

I have a matrix simular to the one below: 1 2 2 3 3 4 4 5 5 6 6 7 7 8 Is there a command that will give me an equation for a line of best fit for these data points? Thanks On Sep 27, 4:16=A0pm, "Charles " <charles.vaug...@colorado.edu> wrote: > I have a matrix simular to the one below: > > =A0 =A0 =A01 =A0 =A0 2 > =A0 =A0 =A02 =A0 =A0 3 > =A0 =A0 =A03 =A0 =A0 4 > =A0 =A0 =A04 =A0 =A0 5 > =A0 =A0 =A05 =A0 =A0 6 > =A0 =A0 =A06 =A0 =A0 7 > =A0 =A0 =A07 =A0 =A0 8 > > Is there a comm...

Hello All: I am trying to compare an observed dataset with best-fit models for: 1) Power Law 2) Exponential 3) Exponential Truncated Power Law I am able to get these four datasets (observed data + 3 models). But now I wish to see which of the models fits the dataset the best. It seems MATLAB AIC will only fit your data to built-in models, and not these 3 models I approximated myself. Any suggestions for procedures (whether or not they use MATLAB or AIC) will be very helpful!! Thank you. Jo PS: The datasets are not the same size (i.e. observed x=50 points, y=50 points. models x=1030 poi...

I want to add a linear trendline in both the plots of subplot. How do i do this, when i do this using the basic fitting option from the tools menu of figure, the line appears only for one data set ata time, i want to do it for both the data sets. You're right, it doesn't seem possible to do it with the Basic Fitting tool. I guess you have to do it by hand, like this: %%%%% x=[0:0.005:1.5]; %curve 1 y=sin(x); %linear fit 1 p = polyfit(x,y,1) y_lin = polyval(p,x); %curve 2 z=cos(x); %linear fit 2 p = polyfit(x,z,1) z_lin = polyval(p,x); %plot subplot(1,2,1) h(1)=plot(x,y) hold on h(2)=...

At the moment I am writing code to find the weighted line of best fit. I can calculate the line of best fit using the code given below, where sortWLAN corresponds to the entries in an array, which I want to extract. onedist = sortWLAN(3,1:100); onerssi = sortWLAN(4,1:100); onewgt = sortWLAN(5,1:100); coeffs = polyfit(onedist,onerssi, coefficient); curvefit = polyval(coeffs, distance); hold on plot(onedist, onerssi, 'o'); plot(distance,curvefit, 'r'); hold off Anybode have any ideas? Cheers Brad wrote: > At the moment I am writing code to find the weighted line of best &...

Hi guys, I have an issue I'd like some help with. coordinates = 107.35 107 111.51 146 117 154.61 111.29 114 In the above matrix 'coordinates', its actually in the form [ x1 y1 x2 y2] for each of the 2 rows. Is there any function I can obtain a best fit line using these 4 points? thanks Kurtis Go look up the demo on the function polyfit, u can tell it to make a first order regression of those...

I have a set of data in an array (11000,207). I've been asked to detrend the data in each of the 207 columns individually. I've tried using the Matlab detrend but I cant get it to work in a sensible way for this data. Instead I've been trying to ouput the equation for a line of best fit for the data in each column and then subtract that from the data. Seems a simple task but the only way I have found to find a line of best fit is doing it manually once you have a figure up using the best fitting option in tools. Obviously I don't want to do this manually 207 times. Does any...

I have two vectors and plotted them using a stem graph. I want to find the line of best fit and display this on the graph. I know about the function polyfit, but how do I graph its output? Look at help polyval cheers Peter wrote: > > > I have two vectors and plotted them using a stem graph. I want to > find the line of best fit and display this on the graph. I know > about > the function polyfit, but how do I graph its output? ...

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