# How to plot only points which lie in a certain range

I'm sorry for this newbie question. I have a data file consisting of 3
columns, and want to plot the first versus the second column, but only if
the parameter in the third column lies in a certain range. Does somebody
have an idea how to do that?

···

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import numpy as np
import numpy as ma
import matplotlib.pyplot as mpl

x = ma.arange(10)
y = ma.array(np.random.rand(10))
z = ma.array(np.random.rand(10))
(z_lo, z_up) = (0.1, 0.8)
x[ (z<z_lo) | (z>z_up) ] = ma.masked
mpl.plot(x,y, 'ok-')

Alternatively,

x = ma.masked_where((z<z_lo) | (z>z_up), x)

···

On Monday 27 October 2008 18:40:07 marcusantonius wrote:

I'm sorry for this newbie question. I have a data file consisting of 3
columns, and want to plot the first versus the second column, but only if
the parameter in the third column lies in a certain range. Does somebody
have an idea how to do that?

You need to use the numpy ‘where’ functionality

import numpy as np

unpack=True) # or similar

# x, y and z are now numpy arrays and

have built in functionality as follows:

s = (z < 10.0) & (z**2 > 0.5)

# or some other constraint. Produces an array ‘s’ of boolean

values

plot(x[s], y[s]) # will plot only
those x,y pairs for which s is True

marcusantonius <markus.haider@…2356…>
28/10/2008 09:40 AM

To

Subject

[Matplotlib-users] How to plot only
points which lie in a certain range

`

I’m sorry for this newbie question. I have a data file consisting of 3

columns, and want to plot the first versus the second column, but only
if

the parameter in the third column lies in a certain range. Does somebody

have an idea how to do that?

···

View this message in context: http://www.nabble.com/How-to-plot-only-points-which-lie-in-a-certain-range-tp20178863p20178863.html

Sent from the matplotlib - users mailing list archive at Nabble.com.

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