Skip to main content

pm3d map of gnuplot in matplotlib

In gnuplot pm3d map plot a 3d data into a surface with color as value of "z".
Lets say we have a data file something like this ..
0.00    0.00    0.00
0.00    1.00    0.00
0.00    2.00    0.00
0.00    3.00    1.9358
0.00    4.00    3.618
0.00    5.00    5.17
0.00    6.00    6.93
0.00    7.00    8.82
0.00    8.00    10.692
1.00    0.00    0.00
1.00    1.00    0.00
1.00    2.00    0.00
1.00    3.00    2.1318
....
...
In gnuplot prompt we will do something like this .
set pm3d map; set dgrid  20,20
sp "data.dat" u 1:2:3 
 and this will produce a figure something like a figure as shown above.
One  of the big disadvantage of gnuplot in my opinion is not able to manipulate
data. Specifically if you look at the way interpolation is done. There is very little you can do with you data.

Here i will give you a simple example how to plot a 3d data
(3 column data or x,y,z ) in python name with the help of matplotlib/numpy/scipy.
One has to first make to data into 2d grid data. This is where the interpolation goes into. There are many different interpolation method one can use depending upon the requirement.


import numpy as np
import matplotlib.pyplot as pl
from scipy.interpolate import griddata

z=np.loadtxt("data.dat",usecols=[0,1,2],unpack=True)
x=np.arange(0,10.1,0.10)
y=np.arange(0,8.1,0.10)
zi=griddata((z[0],z[1]),z[2],(x[None,:], y[:,None]), method='cubic')
pl.imshow(zi,origin="lower",vmin=0,cmap="hot",aspect="auto",extent=[0,10,0,8])
pl.xlabel("U")
pl.ylabel("V")
pl.title("Zero-Temp gap ")
pl.colorbar()
pl.savefig("outAF.pdf")





reference
1. matplotlib   Homepage http://matplotlib.org/
2. scipy griddata documentation  Griddata

Comments

Post a Comment

Popular posts from this blog

Filling between curves with color gradient or cmap in Matplotlib

I was trying to plot fill_between () in matplotlib with color gradient or any cmap defined in pyplot.  After googleing a lot i couldn't find any solution.  An alternative method is to use imshow() . I have created this example :  import numpy as np import matplotlib.pyplot as plt from matplotlib.path import Path from matplotlib.patches import PathPatch xx=np.arange(0,10,0.01) yy=xx*np.exp(-xx) path = Path(np.array([xx,yy]).transpose()) patch = PathPatch(path, facecolor='none') plt.gca().add_patch(patch) im = plt.imshow(xx.reshape(yy.size,1),  cmap=plt.cm.Reds,interpolation="bicubic",                 origin='lower',extent=[0,10,-0.0,0.40],aspect="auto", clip_path=patch, clip_on=True) #im.set_clip_path(patch) plt.savefig("out.png") Source: Matplotlib Example  http://matplotlib.org/examples/pylab_examples/image_clip_path.html  

Installing Latex in mac

Installing latex in mac is very easy if you want to install the full mactex package. But the only  problem is it huge in size (~2GB). An alternative way to install the smaller mactex package. This will   not install some files which might be needed for your .tex file to compile. If you compile by pdflatex it will give some warning like this ! LaTeX Error: File `footmisc.sty' not found. Type X to quit or to proceed, or enter new name. (Default extension: sty) Then you should paste this command in terminal  sudo tlmgr install footmisc collection-fontsrecommended  Similarly if pdflatex complain about any other missing .sty file then install that just  using the above command. I couldn't install psboxit package in the way I described above. This is because psboxit is an absolute package and it is no longer available from the repository. To install this package i did this . cd /usr/local/texlive/2015basic/texmf-dist/tex/latex/  (In...