Re: [Matplotlib-users] plotting scattered data from array

[Oz N. <na...@gm...>]

Hi,
Thanks for your reply and appologies for my late response.
This indeed does the job. But after playing a little bit with the code, I
have discovered a few things:
first, I'd rather work with lists not tuples so I could actually change my
huge array of points.
second the array I described is kind of a pseudo 2D:
It has one big row.
head = [[0,    0,    10],
       [1,    0,    13],
       [2,    0,    11],
       [3,    0,    12],
       [1,    2,    11]]

When I try to use a 3D array, with rows and columns

import pylab as pl

head = [[[0,    0,    10],  [0,    1,    13]],
           [[1,    0,    11],   [1,    1,    12]],
           [[2,    1,    11],   [2,    2,    14]]]

x, y, z = zip(*head)
xi, yi = pl.arange(0, 4, 0.1), pl.arange(0, 3, 0.1)
g = pl.griddata(x, y, z, xi, yi)
pl.scatter(x, y)
pl.contour(xi, yi, g)
pl.show()

I get this error:
Traceback (most recent call last):
  File "asfplot.py", line 9, in <module>
    x, y, z = zip(*head)
ValueError: need more than 2 values to unpack


On Sat, Sep 20, 2008 at 2:19 PM, Goyo <goy...@gm...> wrote:

> Try something like this:
>
> import pylab as pl
>
> head = ((0,    0,    10),
>        (1,    0,    13),
>        (2,    0,    11),
>        (3,    0,    12),
>        (1,    2,    11))
>
> x, y, z = zip(*head)
> xi, yi = pl.arange(0, 4, 0.1), pl.arange(0, 3, 0.1)
> g = pl.griddata(x, y, z, xi, yi)
> pl.scatter(x, y)
> pl.contour(xi, yi, g)
>
> Level values are automatically chosen in this example but you can
> provide the number of values or a sequence of them.
>
> Note that no extrapolation is done outside convex hull defined by input
> data.
>
> Goyo
>
> El sáb, 20-09-2008 a las 11:13 +0200, Oz Nahum escribió:
> > I'm trying again to understand how to plot scattered data from array into
> >    contour graph.
> >    I looked at
> >
> http://www.scipy.org/Cookbook/Matplotlib/Gridding_irregularly_spaced_data
> >    and I understand I have to grid my data. However, in most samples the
> plot
> >    is of a function.
> >    Let's say I want to plot some geological data, suppose water table
> head, and
> >    I have the following 3D aray
> >                x     y    head
> >    head =  ((0,    0,    10),
> >                (1,    0,    13),
> >                (2,    0,    11),
> >                (3,    0,    12),
> >                (1,    2,    11))
> >    matplotlib has lot's of restrictions about how I can plot and
> interpolate
> >    the data, which causes a lot of confusion in my side...
> >    I'll be happy if someone could supply me a clue of how to plot
> contours of
> >    data which comes in arrays or raster format and not an equation.
> >    Thanks,
> >    Oz
> >
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>


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