Hi,
I woud like to draw a vector field using pylab.
quivert looks nice but it sould not scale the arrows to fit my use-case.
quiver([1],[1],[1.2],[1.2]) does plot a nice arrow but the head of the arrow is not at (1.2,1.2).
Is there a way to plot a list of arrows *without* any scaling?
Xavier
Hi Xavier,
You can pass some handy keyword arguments to fix that. Use the following:
quiver([1],[1],[1.2],[1.2], angles='xy', scale_units='xy', scale=1)
Hope that helps 
Regards,
-- Damon
--------------------------
Damon McDougall
Mathematics Institute
University of Warwick
Coventry
CV4 7AL
d.mcdougall@...831...
On 22 Nov 2009, at 16:37, Xavier Gnata wrote:
Hi,
I woud like to draw a vector field using pylab.
quivert looks nice but it sould not scale the arrows to fit my use-case.
quiver([1],[1],[1.2],[1.2]) does plot a nice arrow but the head of the
arrow is not at (1.2,1.2).
Is there a way to plot a list of arrows *without* any scaling?Xavier
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Hi,
RTFM...indeed it works.
However, the axis do not scale accordingly:
quiver([1],[1],[2],[2], angles='xy', scale_units='xy', scale=1) on a TkAgg backend produce a plot with:
In [11]: axis()
Out[11]:
(0.94000000000000006,
1.0600000000000001,
0.94000000000000006,
1.0600000000000001)
The display area scales the same way as it does using quiver([1],[1],[2],[2]) (without any other args).
It looks like a bug.
Xavier
Hi Xavier,
You can pass some handy keyword arguments to fix that. Use the following:
quiver([1],[1],[1.2],[1.2], angles='xy', scale_units='xy', scale=1)
Hope that helps
Regards,
-- Damon--------------------------
Damon McDougall
Mathematics Institute
University of Warwick
Coventry
CV4 7AL
d.mcdougall@...831...On 22 Nov 2009, at 16:37, Xavier Gnata wrote:
Hi,
I woud like to draw a vector field using pylab.
quivert looks nice but it sould not scale the arrows to fit my use-case.
quiver([1],[1],[1.2],[1.2]) does plot a nice arrow but the head of the
arrow is not at (1.2,1.2).
Is there a way to plot a list of arrows *without* any scaling?Xavier
------------------------------------------------------------------------------
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Hi Xavier (cc list),
It may be a bug, however I do not know what the default behaviour 'should' be. You could do:
lims = [-4, 4, -4, 4]
axis(lims)
after calling quiver to see the whole arrow. I did notice that calling
axis('tight')
threw the following error
/Users/Damon/python/lib/matplotlib/axes.py:2038: UserWarning: Attempting to set identical xmin==xmax results in singular transformations; automatically expanding. xmin=1.0, xmax=1.0
warnings.warn('Attempting to set identical xmin==xmax results in singular transformations; automatically expanding. xmin=%s, xmax=%s'%(xmin, xmax))
/Users/Damon/python/lib/matplotlib/axes.py:2212: UserWarning: Attempting to set identical ymin==ymax results in singular transformations; automatically expanding. ymin=1.0, ymax=1.0
warnings.warn('Attempting to set identical ymin==ymax results in singular transformations; automatically expanding. ymin=%s, ymax=%s'%(ymin, ymax))
is this correct, or is it a bug? I'm using "ipython -pylab" with the MacOSX backend. I was expecting axis('tight') would scale the axes so I could see the whole arrow.
Regards,
-- Damon
--------------------------
Damon McDougall
Mathematics Institute
University of Warwick
Coventry
CV4 7AL
d.mcdougall@...831...
On 22 Nov 2009, at 21:34, Xavier Gnata wrote:
Hi,
RTFM...indeed it works.
However, the axis do not scale accordingly:quiver([1],[1],[2],[2], angles='xy', scale_units='xy', scale=1) on a TkAgg backend produce a plot with:
In [11]: axis()
Out[11]:
(0.94000000000000006,
1.0600000000000001,
0.94000000000000006,
1.0600000000000001)The display area scales the same way as it does using quiver([1],[1],[2],[2]) (without any other args).
It looks like a bug.Xavier
Hi Xavier,
You can pass some handy keyword arguments to fix that. Use the following:
quiver([1],[1],[1.2],[1.2], angles='xy', scale_units='xy', scale=1)
Hope that helps
Regards,
-- Damon--------------------------
Damon McDougall
Mathematics Institute
University of Warwick
Coventry
CV4 7AL
d.mcdougall@...831...On 22 Nov 2009, at 16:37, Xavier Gnata wrote:
Hi,
I woud like to draw a vector field using pylab.
quivert looks nice but it sould not scale the arrows to fit my use-case.
quiver([1],[1],[1.2],[1.2]) does plot a nice arrow but the head of the
arrow is not at (1.2,1.2).
Is there a way to plot a list of arrows *without* any scaling?Xavier
------------------------------------------------------------------------------
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trial. Simplify your report design, integration and deployment - and focus on
what you do best, core application coding. Discover what's new with
Crystal Reports now. http://p.sf.net/sfu/bobj-july
_______________________________________________
Matplotlib-users mailing list
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Hi,
Well when you plot, imshow or whatever is matplotlib related, the axes do scale *automatically*.
Why should it be different with quiver?
I do reproduce your error with axis('tight')
Xavier
Hi Xavier (cc list),
It may be a bug, however I do not know what the default behaviour 'should' be. You could do:
lims = [-4, 4, -4, 4]
axis(lims)after calling quiver to see the whole arrow. I did notice that calling
axis('tight')
threw the following error
/Users/Damon/python/lib/matplotlib/axes.py:2038: UserWarning: Attempting to set identical xmin==xmax results in singular transformations; automatically expanding. xmin=1.0, xmax=1.0
warnings.warn('Attempting to set identical xmin==xmax results in singular transformations; automatically expanding. xmin=%s, xmax=%s'%(xmin, xmax))
/Users/Damon/python/lib/matplotlib/axes.py:2212: UserWarning: Attempting to set identical ymin==ymax results in singular transformations; automatically expanding. ymin=1.0, ymax=1.0
warnings.warn('Attempting to set identical ymin==ymax results in singular transformations; automatically expanding. ymin=%s, ymax=%s'%(ymin, ymax))is this correct, or is it a bug? I'm using "ipython -pylab" with the MacOSX backend. I was expecting axis('tight') would scale the axes so I could see the whole arrow.
Regards,
-- Damon--------------------------
Damon McDougall
Mathematics Institute
University of Warwick
Coventry
CV4 7AL
d.mcdougall@...831...On 22 Nov 2009, at 21:34, Xavier Gnata wrote:
Hi,
RTFM...indeed it works.
However, the axis do not scale accordingly:quiver([1],[1],[2],[2], angles='xy', scale_units='xy', scale=1) on a TkAgg backend produce a plot with:
In [11]: axis()
Out[11]:
(0.94000000000000006,
1.0600000000000001,
0.94000000000000006,
1.0600000000000001)The display area scales the same way as it does using quiver([1],[1],[2],[2]) (without any other args).
It looks like a bug.Xavier
Hi Xavier,
You can pass some handy keyword arguments to fix that. Use the following:
quiver([1],[1],[1.2],[1.2], angles='xy', scale_units='xy', scale=1)
Hope that helps
Regards,
-- Damon--------------------------
Damon McDougall
Mathematics Institute
University of Warwick
Coventry
CV4 7AL
d.mcdougall@...831...On 22 Nov 2009, at 16:37, Xavier Gnata wrote:
Hi,
I woud like to draw a vector field using pylab.
quivert looks nice but it sould not scale the arrows to fit my use-case.
quiver([1],[1],[1.2],[1.2]) does plot a nice arrow but the head of the
arrow is not at (1.2,1.2).
Is there a way to plot a list of arrows *without* any scaling?Xavier
------------------------------------------------------------------------------
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trial. Simplify your report design, integration and deployment - and focus on
what you do best, core application coding. Discover what's new with
Crystal Reports now. http://p.sf.net/sfu/bobj-july
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Hi Xavier,
I'm sorry. As I don't know a great deal about the nuts and bolts of matplotlib, I don't think I'm well enough equipped to answer your question. Perhaps someone else on this list can help out?
Regards,
-- Damon
--------------------------
Damon McDougall
Mathematics Institute
University of Warwick
Coventry
CV4 7AL
d.mcdougall@...831...
On 23 Nov 2009, at 21:00, Xavier Gnata wrote:
Hi,
Well when you plot, imshow or whatever is matplotlib related, the axes do scale *automatically*.
Why should it be different with quiver?I do reproduce your error with axis('tight')
Xavier
Hi Xavier (cc list),
It may be a bug, however I do not know what the default behaviour 'should' be. You could do:
lims = [-4, 4, -4, 4]
axis(lims)after calling quiver to see the whole arrow. I did notice that calling
axis('tight')
threw the following error
/Users/Damon/python/lib/matplotlib/axes.py:2038: UserWarning: Attempting to set identical xmin==xmax results in singular transformations; automatically expanding. xmin=1.0, xmax=1.0
warnings.warn('Attempting to set identical xmin==xmax results in singular transformations; automatically expanding. xmin=%s, xmax=%s'%(xmin, xmax))
/Users/Damon/python/lib/matplotlib/axes.py:2212: UserWarning: Attempting to set identical ymin==ymax results in singular transformations; automatically expanding. ymin=1.0, ymax=1.0
warnings.warn('Attempting to set identical ymin==ymax results in singular transformations; automatically expanding. ymin=%s, ymax=%s'%(ymin, ymax))is this correct, or is it a bug? I'm using "ipython -pylab" with the MacOSX backend. I was expecting axis('tight') would scale the axes so I could see the whole arrow.
Regards,
-- Damon--------------------------
Damon McDougall
Mathematics Institute
University of Warwick
Coventry
CV4 7AL
d.mcdougall@...831...On 22 Nov 2009, at 21:34, Xavier Gnata wrote:
Hi,
RTFM...indeed it works.
However, the axis do not scale accordingly:quiver([1],[1],[2],[2], angles='xy', scale_units='xy', scale=1) on a TkAgg backend produce a plot with:
In [11]: axis()
Out[11]:
(0.94000000000000006,
1.0600000000000001,
0.94000000000000006,
1.0600000000000001)The display area scales the same way as it does using quiver([1],[1],[2],[2]) (without any other args).
It looks like a bug.Xavier
Hi Xavier,
You can pass some handy keyword arguments to fix that. Use the following:
quiver([1],[1],[1.2],[1.2], angles='xy', scale_units='xy', scale=1)
Hope that helps
Regards,
-- Damon--------------------------
Damon McDougall
Mathematics Institute
University of Warwick
Coventry
CV4 7AL
d.mcdougall@...831...On 22 Nov 2009, at 16:37, Xavier Gnata wrote:
Hi,
I woud like to draw a vector field using pylab.
quivert looks nice but it sould not scale the arrows to fit my use-case.
quiver([1],[1],[1.2],[1.2]) does plot a nice arrow but the head of the
arrow is not at (1.2,1.2).
Is there a way to plot a list of arrows *without* any scaling?Xavier
------------------------------------------------------------------------------
Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day
trial. Simplify your report design, integration and deployment - and focus on
what you do best, core application coding. Discover what's new with
Crystal Reports now. http://p.sf.net/sfu/bobj-july
_______________________________________________
Matplotlib-users mailing list
Matplotlib-users@lists.sourceforge.net
matplotlib-users List Signup and Options