Re: [Matplotlib-users] ploting a contour graph from data files

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

Here is why the contours are wrong:
they are ploted verticaly, while I think, it is more common to draw temp.
contours in oceanography when the are horizontal.

Also, one more thing, I can't find how to expand the borders of the plot,
say from 350 to 400
(same for depth) I tried usig xlim and ylim(0,900) but no result.
Here is my code now, I can't really get it, ha ?
another issue is that I've added anoter temp. series but it won't show it. I
still see 3 rows.

from matplotlib import pyplot as plt
from pylab import *
temperature=[
            [9,8,6],
            [9,7,6],
            [9,7,6],
            [9,6,6]
]

distance = (0,200,350)
depth = (100,250,250,700)

x = distance
y = depth
z = temperature
#m = plt.contourf(x,y,z)
m = plt.contour(x,y,z)
ylabel('Depth')
xlabel('Distance')
ylim(0,1200)
#plt.xlim(0,500)
plt.gca().invert_yaxis()
#plt.colorbar(m)

import numpy as np
X, Y = np.meshgrid(x,y)
#plt.hold(True) # probably not necessary
plt.plot(X,Y, 'o')
plt.show(m)


On Wed, Jul 16, 2008 at 10:28 PM, Eric Firing <ef...@ha...> wrote:

> Oz Nahum wrote:
>
>> Hi Eric,
>> really thanks for your help so far. I am doing a quick short course, and
>> I'll do the examples later.
>> I've fixed the code, here it is:
>>
>> from matplotlib import pyplot as plt
>> temperature=[
>>            [10,8,6],
>>            [9,7,5],
>>            [8,7,4]
>> ]
>>
>> distance = (100,200,300)
>> depth = (100,300,700)
>>
>> x = distance
>> y = depth
>> z = temperature
>>
>> m = plt.contourf(x,y,z)
>> plt.gca().invert_yaxis()
>> plt.colorbar(m)
>> plt.show(m)
>>
>> the trouble now that the contours seems wrong... and my question still
>> stands. I'd like to do the plot as said: contours + series, can you show me
>> where I'm wrong ?
>>
>
> The plot looks right to me--I see 4 degrees in the lower RH corner, 300
>  distance units and 700 depth units.  Why do you say the contours seem
> wrong?
>
> As for plotting the "series", what do you mean?  Put circles on the data
> points?  Then include something like this, after the call to contourf:
>
> import numpy as np
> X, Y = np.meshgrid(x,y)
> plt.hold(True) # probably not necessary
> plt.plot(X,Y, 'o')
>
>
>
> Eric
>
>>
>> thanks, Oz
>>
>>
>> On Wed, Jul 16, 2008 at 9:37 PM, Eric Firing <ef...@ha... <mailto:
>> ef...@ha...>> wrote:
>>
>>    Oz Nahum wrote:
>>
>>        Ok, I played with it a little bit.
>>
>>        Here is what I know:
>>        importing the data is not a big issue, I aready wrote a tutorial
>>        about it here:
>>        http://www.tabula0rasa.org/?p=21
>>
>>        here is a sample code I wrote.
>>        from matplotlib import pyplot as plt
>>        from pylab import *
>>        temperature=[
>>                   [1,3,4],
>>                   [2,4,5],
>>                   [6,3,2]
>>        ]
>>
>>        distance = (100,200,300)
>>        depth = (10,30,50)
>>
>>        plt.colorbar()
>>        plt.contourf(distance,depth,temperature)
>>        plt.gca().invert_yaxis()
>>        plt.show()
>>
>>
>>
>>        Can I plot the dots as different series on top of the contours ?
>>
>>
>>    First you have to make your basic example work; what you posted
>>    above does not.
>>    1) For an example like this, use a different number of points in the
>>    x and y directions, to make it clear how the arrays are oriented.
>>    2) The colorbar command must *follow* the contourf command.
>>    3) Make your test temperature profiles more reasonable, i.e.
>>    temperature decreasing with depth, so you can see whether your plot
>>    is doing the right thing.
>>    4) Omit the "from pylab import *"
>>    5) Once you start doing real work, you will need numpy.  The
>>    suggested import syntax is "import numpy as np".
>>    6) Study the examples that come with mpl.
>>
>>    Eric
>>
>>
>>
>