Develop Reference

End points of 3D surface being connected

I have this set of data, which I would like to plot it in a 3D surface and in a contour by using python (numpy and matplotlib, basically). In this case, I have the X and Y axis as my free coordinates, and the results are described as a dataset on the z-axis.
I've checked many times the data, and it is formatted correctly to my needs.
Here is a plot of the set in a scatter manner
The problem is when I try to use the surface plot, where the end points of the (X, Y) mesh are connected, closing the surface and making not visible the part of the image that contains the information I would like to have. Here is the output I have regarding the surface plot and here is the output regarding the contour plot.
The code related to the surface plot (only ploting part) is
#...
#X and Y are the coordinates values
#E is the results I am trying to plot
fig = plt.figure()
ax = fig.gca(projection='3d')
surf = ax.plot_surface(X, Y, E, cmap=cm.coolwarm, linewidth=0, antialiased=False)
ax.scatter3D(X, Y, E, cmap='Greens')
fig.colorbar(surf, shrink=0.5, aspect=5)
plt.show()
Here is the code related to the contour plot
fig, ax = plt.subplots()
CS = ax.contourf(X, Y, E, 10, cmap='RdGy')
ax.clabel(CS, inline=1, fontsize=10)
ax.set_title('Simplest default with labels')
fig.colorbar(CS, shrink=0.5, aspect=5)
plt.show()

Relocate colorbar

Is it possible to put the color diagram (which is now on the right side of the original figure) on the top of the figure?
My code:
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d.axes3d import Axes3D, get_test_data
from matplotlib import cm
import numpy as np
# set up a figure twice as wide as it is tall
fig = plt.figure(figsize=plt.figaspect(0.5))
#===============
# First subplot
#===============
# set up the axes for the first plot
ax = fig.add_subplot(1, 2, 1, projection='3d')
# plot a 3D surface like in the example mplot3d/surface3d_demo
X = np.arange(-5, 5, 0.25)
Y = np.arange(-5, 5, 0.25)
X, Y = np.meshgrid(X, Y)
R = np.sqrt(X**2 + Y**2)
Z = np.sin(R)
surf = ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=cm.coolwarm,
linewidth=0, antialiased=False)
ax.set_zlim(-1.01, 1.01)
fig.colorbar(surf, shrink=0.5, aspect=10)
fig.savefig('64bit.png')

You have to add additional axes (add_axes) to put your colorbar at the desired position:
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d.axes3d import Axes3D, get_test_data
from matplotlib import cm
from mpl_toolkits.axes_grid1 import make_axes_locatable
import numpy as np
# set up a figure twice as wide as it is tall
fig = plt.figure(figsize=plt.figaspect(0.5))
#===============
# First subplot
#===============
# set up the axes for the first plot
ax = fig.add_subplot(1, 2, 1, projection='3d')
# plot a 3D surface like in the example mplot3d/surface3d_demo
X = np.arange(-5, 5, 0.25)
Y = np.arange(-5, 5, 0.25)
X, Y = np.meshgrid(X, Y)
R = np.sqrt(X**2 + Y**2)
Z = np.sin(R)
surf = ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=cm.coolwarm,
linewidth=0, antialiased=False)
ax.set_zlim(-1.01, 1.01)
# position of colorbar
# where arg is [left, bottom, width, height]
cax = fig.add_axes([0.15, .87, 0.35, 0.03])
fig.colorbar(surf, orientation='horizontal', cax=cax)
plt.show()

Yes it is, there are multiple answers here in the site showing you how to move the colorbar around like this one: positioning the colorbar
In your case, you want to combine that with the orientation argument. As far as I know, there is no easy way of just placing the colorbar to the top of your figure automatically, you will have to place it manually. Here is my code that replaces your fig.colorbar(surf, shrink=0.5, aspect=10):
cbax = fig.add_axes([0.1, 0.89, 0.5, 0.05])
fig.colorbar(surf, orientation="horizontal", cax=cbax)
The numbers in the list describe some characteristics of the colorbar which are [left, bottom, width, height] as mentioned in the other answer that I have attached.
These numbers came out nicely for your plot, feel free to change them to your liking.

In order to get the colorbar on top of the plot you need to create some axes, designated to host the colorbar.
This can either be done manually by placing a new axes at some given position in figure coordinates,
cax = fig.add_axes([0.2,0.8,0.3,.05])
fig.colorbar(surf, cax=cax, orientation="horizontal")
or, by using a subplot grid (gridspec), which is shown in the following:
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d.axes3d import Axes3D
import matplotlib.gridspec as gridspec
import numpy as np
x = np.arange(-5, 5, 0.25)
X, Y = np.meshgrid(x,x)
Z = np.sin(np.sqrt(X**2 + Y**2))
gs = gridspec.GridSpec(2, 2, height_ratios=[0.05,1])
fig = plt.figure()
ax = fig.add_subplot(gs[1,0], projection='3d')
cax = fig.add_subplot(gs[0,0])
surf = ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap="coolwarm",
linewidth=0, antialiased=False, vmin=-1, vmax=1)
fig.colorbar(surf, cax=cax, orientation="horizontal", ticks=[-1,0,1])
plt.show()

For a method which avoids having to manually create new axes and instead allows us to keep the colorbar linked to an existing plot axis, we can use the location keyword (method adapted initially from here).
The location argument is meant to be used on colorbars which reference multiple axes in a list (and will throw an error if colorbar is given only one axis), but if you simply put your one axis in a list, it will allow you to use the argument. You can use the following code as an example:
import matplotlib.pyplot as plt
import numpy as np
fig = plt.figure()
ax = fig.add_subplot(111)
axp = ax.imshow(np.random.randint(0, 100, (100, 100)))
cb = plt.colorbar(axp,ax=[ax],location='top')
plt.show()
which yields this plot. From here, you can edit the colorbar using the typical methods (pad, shrink, etc.) to further tune the appearance of your plot.
Fair warning, I haven't seen this method used many other places and it could be less robust than going through the extra steps of creating a new axis for your colorbar.

Color of surface plots turning black after saving- Python

Why will my surface plot colour change from the 1st to the second in terms of colour?
The following is my code for the plot:
def Plots3d(U):
fig = plt.figure()
ax = fig.gca(projection='3d')
y, x = U.shape
Y = np.arange(0, y, 1)
X = np.arange(0, x, 1)
Y, X = np.meshgrid(Y, X)
Z = U[Y, X]
ax.plot_surface(X, Y, Z, rstride=1, cstride=1,
linewidth=0.7, antialiased=False, cmap = cm.summer)
plt.xlabel('Stock Price Nodes')
plt.ylabel('Timesteps')
plt.title('Analytical solution surface for 0 <= t <= 2')
plt.show()

This looks like a resolution problem: the lines in the saved plot are too thick and are dominating the figure when saved, turning it black. The default resolution of a saved figure and a figure produced with plt.show are probably different in your matplotlibrc file.
You could try either increasing the resolution (the dots per square inch, or dpi) or decreasing the linewidth.
A few possible options for you:
Increase dpi with rcParams
from matplotlib import rcParams
# this changes the dpi of figures saved from plt.show()
rcParams['figure.dpi'] = 300
# this changes the dpi of figures saved from plt.savefig()
rcParams['savefig.dpi'] = 300
Increase dpi during savefig
If you don't want to use rcParams, you can just increase the dpi as you save the figure:
plt.savefig('myfigure.png', dpi=300)
Decreasing linewidth
Alternatively, you could try decreasing the linewidth of the surface plot
ax.plot_surface(X, Y, Z, rstride=1, cstride=1,
linewidth=0.3, antialiased=False, cmap = cm.summer)

mplot3d narrow spline surface missing from output

I have setup mplot3d to provide a 3D surface plot per the example.
When I plot my data I am seeing that the surface is missing from a ridge running through the surface (see image). I noticed that surface filling appears to follow the stride but the grid-lines make viewing difficult at lower step sizes.
from mpl_toolkits.mplot3d import axes3d
from matplotlib import cm, pyplot
import numpy
Z = data[-300::]
X,Y = numpy.mgrid[:len(Z), :len(Z[0])]
fig = pyplot.figure(figsize=(20, 10), dpi=800)
ax = fig.gca(projection='3d')
surf = ax.plot_surface(X,
Y,
Z,
rstride=len(Z)/5,
cstride=len(Z[0])/10,
alpha=.6,
linewidths=(.5,),
antialiased=True,
cmap=cm.coolwarm,
vmin=124,
vmax=186
)
cset = ax.contourf(X, Y, Z, zdir='z', offset=130, cmap=cm.coolwarm, vmin=124, vmax=186)
ax.set_xlim(len(Z) * 1.2, 0)
ax.set_ylim(0, len(Z[0]) * 1.2)
ax.elev = 25
ax.azim = 20
cb = fig.colorbar(surf, shrink=0.5, aspect=5)
Is there a way to fill the missing surface?

The only way i have found to accomplish this is by setting the stride to one and linewidth to 0. The downside to this is that I appear to lose the grid overlay.
surf = ax.plot_surface(X,
Y,
Z,
shade=True,
rstride=1, cstride=1, linewidth=0,
linewidths=(.5,),
antialiased=True,
)

Python colorbar scale

I have a question regarding the colorbar of the matplotlib. I have a surface-plot, which is working fine, and the colors are used correctly. But somehow, the scale of my colorbar is messed up. I think it should go from 0 to 0.4. But the actual code gives me 0 to 0.16. What am I missing here? Strange that the value 0.16 is the square of 0.4.
Here is my plot:
And of course, here is my code:
values_all = zip(*values_all)
x = range(len(values_all[0]))
y = range(len(values_all))
figure = plt.figure(1, figsize=(10, 7))
ax = Axes3D(figure, azim=-124, elev=40, zlim=(0, 0.4))
x, y = np.meshgrid(x, y)
surface = ax.plot_surface(x, y, values_all, linewidth=0, rstride=1, cstride=1, cmap=cm.jet)
plt.colorbar(surface, shrink=0.4, aspect=10)
plt.show()
If I edit my code the following way, the colorbar is scaled correctly, but the plot itself is not colored correctly anymore:
surface = ax.plot_surface(x, y, values_all, linewidth=0, rstride=1, cstride=1, cmap=cm.jet,vmin=0,vmax=0.4)
Results in:
With other sample data, you can see that this is not only an issue of the plot's borders (The values that are giving the strange peak are between 0.3-0.35):