rescaling a matplotlib.colorbar and matplotlib.contour after creation

I have a contourplot, generated using matplotlib.

import numpy as np

import matplotlib.pyplot as plt



X = np.linspace(-10, 10, 100)

Y = np.linspace(-10, 10, 100)

XX, YY = np.meshgrid(X, Y)

ZZ = XX**2 + YY**2

levels = np.linspace(0, 200, 10)



fig, ax = plt.subplots()

cf = ax.contourf(X, Y, ZZ, levels=levels)

cbar = fig.colorbar(cf)

This generates this figure:

enter image description here

Now imagine, that for some reason, the figure is handed to the user through some functions call, and the user only gets the ax, fig, and cbar objects.

UPDATE: The reason I want to do this, is because I have to make a gargantuan amount of contourplots in an automated way. I have automated the creation of the contourplot in the backend (vaguely described as "the function call" here above). But for some plots, some slight modification is required to generated exquisite plots. So instead of manipulating the backed or having to add numerous amounts of options for every situation, it would be nice if the couple of figures I need to adjust out of the +400 figures are adjustable through the ax, fig, and cbar objects.

Now only manipulating those objects, I want to zoom in, and rescale both the colorbar as well as the levels.

Zooming in:

ax.set_xlim(2.5, 7.5)

ax.set_ylim(2.5, 7.5)

enter image description here

Changing the limit on the colorbar and the ticks:

new_clim = (0, 100)

# find location of the new upper limit on the color bar

loc_on_cbar = cbar.norm(new_clim[1])

# redefine limits of the colorbar

cf.colorbar.set_clim(*new_clim)

cf.colorbar.set_ticks(np.linspace(*new_clim, 10))

# redefine the limits of the levels of the contour

cf.set_clim(*new_clim)

# updating the contourplot

cf.changed()

enter image description here

Changing the scale of the colorbar itself:

cbar.ax.set_ylim(0, loc_on_cbar)

cbar.ax.autoscale_view()

enter image description here

Now there are some issues here:

I cannot seem the find how to rescale the colorbar's axis without having that annoying empty rectangle on top.

I cannot find howto adjust the number of levels in the contourplot & colorbar after creating the instance.

Thanks a lot!

edited Nov 23 '18 at 9:01

asked Nov 23 '18 at 8:41

Daan

800819

I don't think that you can change the number of levels of cf after creation. The contourf function returns a QuadContourSet, which, I think, doesn't have any information on the function from which the contours are derived.

– Thomas Kühn
Nov 23 '18 at 10:00

If you know which plots should be altered before creating them, simply changing the creation method to zooming in on the right location in the first place would be the easiest way to go.

– cheersmate
Nov 23 '18 at 11:18

For the colorbar, have you tried only calling cf.set_clim() and leaving out the other calls (i.e. cf.colorbar.set_clim() and so forth) and then calling fig.canvas.draw() after that?

– Thomas Kühn
Nov 23 '18 at 12:44

@ThomasKühn: Yes, this yields the same result as in figure 3. [Thanks for the tip on the QuadContourSet, I'll check it out.]

– Daan
Nov 23 '18 at 12:51

add a comment |

I have a contourplot, generated using matplotlib.

import numpy as np

import matplotlib.pyplot as plt



X = np.linspace(-10, 10, 100)

Y = np.linspace(-10, 10, 100)

XX, YY = np.meshgrid(X, Y)

ZZ = XX**2 + YY**2

levels = np.linspace(0, 200, 10)



fig, ax = plt.subplots()

cf = ax.contourf(X, Y, ZZ, levels=levels)

cbar = fig.colorbar(cf)

This generates this figure:

enter image description here

Now imagine, that for some reason, the figure is handed to the user through some functions call, and the user only gets the ax, fig, and cbar objects.

Now only manipulating those objects, I want to zoom in, and rescale both the colorbar as well as the levels.

Zooming in:

ax.set_xlim(2.5, 7.5)

ax.set_ylim(2.5, 7.5)

enter image description here

Changing the limit on the colorbar and the ticks:

new_clim = (0, 100)

# find location of the new upper limit on the color bar

loc_on_cbar = cbar.norm(new_clim[1])

# redefine limits of the colorbar

cf.colorbar.set_clim(*new_clim)

cf.colorbar.set_ticks(np.linspace(*new_clim, 10))

# redefine the limits of the levels of the contour

cf.set_clim(*new_clim)

# updating the contourplot

cf.changed()

enter image description here

Changing the scale of the colorbar itself:

cbar.ax.set_ylim(0, loc_on_cbar)

cbar.ax.autoscale_view()

enter image description here

Now there are some issues here:

I cannot seem the find how to rescale the colorbar's axis without having that annoying empty rectangle on top.

I cannot find howto adjust the number of levels in the contourplot & colorbar after creating the instance.

Thanks a lot!

edited Nov 23 '18 at 9:01

asked Nov 23 '18 at 8:41

Daan

800819

I don't think that you can change the number of levels of cf after creation. The contourf function returns a QuadContourSet, which, I think, doesn't have any information on the function from which the contours are derived.

– Thomas Kühn
Nov 23 '18 at 10:00

If you know which plots should be altered before creating them, simply changing the creation method to zooming in on the right location in the first place would be the easiest way to go.

– cheersmate
Nov 23 '18 at 11:18

For the colorbar, have you tried only calling cf.set_clim() and leaving out the other calls (i.e. cf.colorbar.set_clim() and so forth) and then calling fig.canvas.draw() after that?

– Thomas Kühn
Nov 23 '18 at 12:44

@ThomasKühn: Yes, this yields the same result as in figure 3. [Thanks for the tip on the QuadContourSet, I'll check it out.]

– Daan
Nov 23 '18 at 12:51

add a comment |

I have a contourplot, generated using matplotlib.

import numpy as np

import matplotlib.pyplot as plt



X = np.linspace(-10, 10, 100)

Y = np.linspace(-10, 10, 100)

XX, YY = np.meshgrid(X, Y)

ZZ = XX**2 + YY**2

levels = np.linspace(0, 200, 10)



fig, ax = plt.subplots()

cf = ax.contourf(X, Y, ZZ, levels=levels)

cbar = fig.colorbar(cf)

This generates this figure:

enter image description here

Now imagine, that for some reason, the figure is handed to the user through some functions call, and the user only gets the ax, fig, and cbar objects.

Now only manipulating those objects, I want to zoom in, and rescale both the colorbar as well as the levels.

Zooming in:

ax.set_xlim(2.5, 7.5)

ax.set_ylim(2.5, 7.5)

enter image description here

Changing the limit on the colorbar and the ticks:

new_clim = (0, 100)

# find location of the new upper limit on the color bar

loc_on_cbar = cbar.norm(new_clim[1])

# redefine limits of the colorbar

cf.colorbar.set_clim(*new_clim)

cf.colorbar.set_ticks(np.linspace(*new_clim, 10))

# redefine the limits of the levels of the contour

cf.set_clim(*new_clim)

# updating the contourplot

cf.changed()

enter image description here

Changing the scale of the colorbar itself:

cbar.ax.set_ylim(0, loc_on_cbar)

cbar.ax.autoscale_view()

enter image description here

Now there are some issues here:

I cannot seem the find how to rescale the colorbar's axis without having that annoying empty rectangle on top.

I cannot find howto adjust the number of levels in the contourplot & colorbar after creating the instance.

Thanks a lot!

edited Nov 23 '18 at 9:01

asked Nov 23 '18 at 8:41

Daan

800819

I have a contourplot, generated using matplotlib.

import numpy as np

import matplotlib.pyplot as plt



X = np.linspace(-10, 10, 100)

Y = np.linspace(-10, 10, 100)

XX, YY = np.meshgrid(X, Y)

ZZ = XX**2 + YY**2

levels = np.linspace(0, 200, 10)



fig, ax = plt.subplots()

cf = ax.contourf(X, Y, ZZ, levels=levels)

cbar = fig.colorbar(cf)

This generates this figure:

enter image description here

Now imagine, that for some reason, the figure is handed to the user through some functions call, and the user only gets the ax, fig, and cbar objects.

Now only manipulating those objects, I want to zoom in, and rescale both the colorbar as well as the levels.

Zooming in:

ax.set_xlim(2.5, 7.5)

ax.set_ylim(2.5, 7.5)

enter image description here

Changing the limit on the colorbar and the ticks:

new_clim = (0, 100)

# find location of the new upper limit on the color bar

loc_on_cbar = cbar.norm(new_clim[1])

# redefine limits of the colorbar

cf.colorbar.set_clim(*new_clim)

cf.colorbar.set_ticks(np.linspace(*new_clim, 10))

# redefine the limits of the levels of the contour

cf.set_clim(*new_clim)

# updating the contourplot

cf.changed()

enter image description here

Changing the scale of the colorbar itself:

cbar.ax.set_ylim(0, loc_on_cbar)

cbar.ax.autoscale_view()

enter image description here

Now there are some issues here:

I cannot seem the find how to rescale the colorbar's axis without having that annoying empty rectangle on top.

I cannot find howto adjust the number of levels in the contourplot & colorbar after creating the instance.

Thanks a lot!

python matplotlib

edited Nov 23 '18 at 9:01

asked Nov 23 '18 at 8:41

Daan

800819

edited Nov 23 '18 at 9:01

asked Nov 23 '18 at 8:41

Daan

800819

edited Nov 23 '18 at 9:01

asked Nov 23 '18 at 8:41

Daan

800819

asked Nov 23 '18 at 8:41

Daan

800819

asked Nov 23 '18 at 8:41

Daan

800819

I don't think that you can change the number of levels of cf after creation. The contourf function returns a QuadContourSet, which, I think, doesn't have any information on the function from which the contours are derived.

– Thomas Kühn
Nov 23 '18 at 10:00

If you know which plots should be altered before creating them, simply changing the creation method to zooming in on the right location in the first place would be the easiest way to go.

– cheersmate
Nov 23 '18 at 11:18

For the colorbar, have you tried only calling cf.set_clim() and leaving out the other calls (i.e. cf.colorbar.set_clim() and so forth) and then calling fig.canvas.draw() after that?

– Thomas Kühn
Nov 23 '18 at 12:44

@ThomasKühn: Yes, this yields the same result as in figure 3. [Thanks for the tip on the QuadContourSet, I'll check it out.]

– Daan
Nov 23 '18 at 12:51

add a comment |

I don't think that you can change the number of levels of cf after creation. The contourf function returns a QuadContourSet, which, I think, doesn't have any information on the function from which the contours are derived.

– Thomas Kühn
Nov 23 '18 at 10:00

If you know which plots should be altered before creating them, simply changing the creation method to zooming in on the right location in the first place would be the easiest way to go.

– cheersmate
Nov 23 '18 at 11:18

For the colorbar, have you tried only calling cf.set_clim() and leaving out the other calls (i.e. cf.colorbar.set_clim() and so forth) and then calling fig.canvas.draw() after that?

– Thomas Kühn
Nov 23 '18 at 12:44

@ThomasKühn: Yes, this yields the same result as in figure 3. [Thanks for the tip on the QuadContourSet, I'll check it out.]

– Daan
Nov 23 '18 at 12:51

I don't think that you can change the number of levels of cf after creation. The contourf function returns a QuadContourSet, which, I think, doesn't have any information on the function from which the contours are derived.

– Thomas Kühn
Nov 23 '18 at 10:00

If you know which plots should be altered before creating them, simply changing the creation method to zooming in on the right location in the first place would be the easiest way to go.

– cheersmate
Nov 23 '18 at 11:18

For the colorbar, have you tried only calling cf.set_clim() and leaving out the other calls (i.e. cf.colorbar.set_clim() and so forth) and then calling fig.canvas.draw() after that?

– Thomas Kühn
Nov 23 '18 at 12:44

@ThomasKühn: Yes, this yields the same result as in figure 3. [Thanks for the tip on the QuadContourSet, I'll check it out.]

– Daan
Nov 23 '18 at 12:51

add a comment |

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