Re: [Matplotlib-users] contourf question
[EMAIL PROTECTED] wrote: Thanks again Eric, Your examples are exactly what I was after. Glad to hear it! My colleague was hypothesizing that there's probably a less-than instead of a less-than-or-equal somewhere, if it is a bug. That was part of it, but it was a little more subtle. I have tweaked the automatic level generation routine so that it now does what one might reasonably expect. Specifying levels explicitly is still better when you can do it; the number-of-levels method is really only for quick and dirty exploratory work, when you don't care too much which levels are chosen and you don't know in advance what the data interval will be. Eric - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] contourf question
Thanks Eric.
However, when I specify the same number of levels as suggested, contourf
divides this example into three regions, with a diagonal 'stripe' instead of a
clean boundary, so I guess I'm asking whether it's possible to trick contourf
into generating a single boundary between the two regions such that it matches
that found by contour?
For the moment, a suitable workaround seems to be to do
contourf(a,1,colors=('w','k'))
where the background colour is white. This generates what I'm after.
I notice also that linewidths is mentioned in the docstring under Obsolete:,
but it seems to do nothing, so it should probably be removed from the docstring.
thanks again,
Gary
Eric Firing [EMAIL PROTECTED] wrote:
Gary Ruben wrote:
I'm notice that contourf behaves differently to contour by default in
where it decides to position contours. For example, using pylab, if you try
a=tri(10)
contourf(a,0)
contour(a,1)
I'd have expected the contours to line up, but they don't. Is there a
way to get contourf to place its contours at the same position as contour?
Specify the same number of levels:
contourf(a,1)
contour(a,1)
That takes care of this simple case. There are other cases, however,
where contour and contourf simply don't agree; contouring is ambiguous,
and only part of the algorithm is shared between contour and contourf.
For well-behaved datasets this is normally not a problem, but it becomes
obvious if you contour a random array.
Eric
-
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Re: [Matplotlib-users] contourf question
[EMAIL PROTECTED] wrote:
Thanks Eric.
However, when I specify the same number of levels as suggested, contourf
divides this example into three regions, with a diagonal 'stripe' instead of
a clean boundary, so I guess I'm asking whether it's possible to trick
contourf into generating a single boundary between the two regions such that
it matches that found by contour?
Now I see the problem; this is something of a corner case, but it may be
pointing to a bug.
Where do you really want the line to fall?
Do you need to specify the number of contours instead of specifying the
actual levels (boundaries)? Are you actually dealing with zeros and
ones as in the example? If so, you probably want
contour(a, [0.5])
contourf(a, [-1, 0.5, 2], colors=('w', 'k'), extend='neither')
or
contourf(a, [0.5, 2], colors=('k',), extend='neither')
In this case you are saying color everything between 0.5 and 2, and
nothing else.
Specifying one contour instead of giving the levels is yielding 0.6;
this is a consequence of using the MaxNLocator by default to auto-select
the levels.
For the moment, a suitable workaround seems to be to do
contourf(a,1,colors=('w','k'))
where the background colour is white. This generates what I'm after.
I notice also that linewidths is mentioned in the docstring under Obsolete:,
but it seems to do nothing, so it should probably be removed from the
docstring.
I will fix the docstring. Thanks.
Eric
thanks again,
Gary
Eric Firing [EMAIL PROTECTED] wrote:
Gary Ruben wrote:
I'm notice that contourf behaves differently to contour by default in
where it decides to position contours. For example, using pylab, if you try
a=tri(10)
contourf(a,0)
contour(a,1)
I'd have expected the contours to line up, but they don't. Is there a
way to get contourf to place its contours at the same position as contour?
Specify the same number of levels:
contourf(a,1)
contour(a,1)
That takes care of this simple case. There are other cases, however,
where contour and contourf simply don't agree; contouring is ambiguous,
and only part of the algorithm is shared between contour and contourf.
For well-behaved datasets this is normally not a problem, but it becomes
obvious if you contour a random array.
Eric
-
This SF.net email is sponsored by: Splunk Inc.
Still grepping through log files to find problems? Stop.
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Re: [Matplotlib-users] contourf question
Thanks again Eric,
Your examples are exactly what I was after.
My colleague was hypothesizing that there's probably a less-than instead of a
less-than-or-equal somewhere, if it is a bug.
regards,
Gary
Eric Firing [EMAIL PROTECTED] wrote:
[EMAIL PROTECTED] wrote:
Thanks Eric.
However, when I specify the same number of levels as suggested, contourf
divides this example into three regions, with a diagonal 'stripe' instead
of a clean boundary, so I guess I'm asking whether it's possible to trick
contourf into generating a single boundary between the two regions such
that it matches that found by contour?
Now I see the problem; this is something of a corner case, but it may be
pointing to a bug.
Where do you really want the line to fall?
Do you need to specify the number of contours instead of specifying the
actual levels (boundaries)? Are you actually dealing with zeros and
ones as in the example? If so, you probably want
contour(a, [0.5])
contourf(a, [-1, 0.5, 2], colors=('w', 'k'), extend='neither')
or
contourf(a, [0.5, 2], colors=('k',), extend='neither')
In this case you are saying color everything between 0.5 and 2, and
nothing else.
Specifying one contour instead of giving the levels is yielding 0.6;
this is a consequence of using the MaxNLocator by default to auto-select
the levels.
For the moment, a suitable workaround seems to be to do
contourf(a,1,colors=('w','k'))
where the background colour is white. This generates what I'm after.
I notice also that linewidths is mentioned in the docstring under
Obsolete:, but it seems to do nothing, so it should probably be removed
from the docstring.
I will fix the docstring. Thanks.
Eric
thanks again,
Gary
Eric Firing [EMAIL PROTECTED] wrote:
Gary Ruben wrote:
I'm notice that contourf behaves differently to contour by default in
where it decides to position contours. For example, using pylab, if you
try
a=tri(10)
contourf(a,0)
contour(a,1)
I'd have expected the contours to line up, but they don't. Is there a
way to get contourf to place its contours at the same position as contour?
Specify the same number of levels:
contourf(a,1)
contour(a,1)
That takes care of this simple case. There are other cases, however,
where contour and contourf simply don't agree; contouring is ambiguous,
and only part of the algorithm is shared between contour and contourf.
For well-behaved datasets this is normally not a problem, but it becomes
obvious if you contour a random array.
Eric
-
This SF.net email is sponsored by: Splunk Inc.
Still grepping through log files to find problems? Stop.
Now Search log events and configuration files using AJAX and a browser.
Download your FREE copy of Splunk now http://get.splunk.com/
___
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