Yes, my data is gridded. And no, I don't plan to sample these density values later. I just want to plot it and see what it looks like :) I'm not sure how to reshape the data into a 2D array though, or how to make a contour plot from a dataset rather than from a function. Is there anything on this in the documentation?
Thanks for your help, Amelia On Friday, May 13, 2016 at 8:30:36 PM UTC-4, Scott T wrote: > > Two key questions - is your data gridded? And do you plan to sample from > these density values later, or are you just wanting to plot it and see what > it looks like? > > If your data is gridded (your ~10000 lines cover every combination of x > and y values in the range that you are interested in), then you can use the > contour command in Gadfly, which is the volcano plot you described. You'll > first need to reshape the data so it's a 2D array: think of it as > displaying a 2D image, where the number at each point is the density. > However, for displaying this kind of data, I prefer heatmaps, and I don't > know if Gadfly supports those - you may have to look into the histogram2d > command. > > If it is not gridded (the x and y points don't have any particular > structure to them), it's still possible, but you have to choose a way to > decide how you want to turn it from unstructured data into a 2D image. The > histogram2d approach that Tom showed above is one option, where you treat > each density measurement as a weighted measurement in a histogram. But if > your data represents single measurements of a function that has meaningful > values away from those measured points, you probably want to interpolate > between those points. For this you can use a package like Dierckx, which > does interpolations on unstructured data. I also have some simple code that > does barycentric triangular interpolation between unstructured points, in > case you wanted to have a look at that. > > This may be overkill, however, if you just want to look at the data and > don't plan to interpolate or draw from those density values later. If > that's the case, the trisurface plot above might be just what you need for > showing you the shape of your density data. > > Whatever you choose, I can recommend Tom's Plots package as a nice > interface to the other plotting packages in Julia - it makes it easy to > switch between different plotting options like Gadfly and PyPlot depending > on what features they offer. > > Cheers, > Scott > > On Friday, 13 May 2016 15:34:19 UTC+1, ameliafit...@gmail.com wrote: >> >> Dear Julia users, >> >> I have a rookie question about plotting in Gadfly. I have some density >> data in a plain-text file in the form of x y d, where d is the density at >> the point (x,y). I have about 10,000 lines of this data. I'm currently >> plotting old-school using gnuplot and since I don't like the looks of what >> I've been able to make, I'm hoping to be able to do something more elegant >> like Gadfly. I'm a relatively new Julia user as well. I like the "volcano" >> contour plot from the Gadfly documentation ( second plot from the top at >> http://dcjones.github.io/Gadfly.jl/geom_contour.html). I'm just not sure >> how to go about it. >> >> Has anyone done something like this before? I think it could be a really >> beautiful way to represent my data if I can get it to work. Any hints or >> suggestions would be greatly appreciated! >> >> Cheers, >> >> Amelia >> >
