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2D images in 3D#
This example demonstrates how to plot 2D color coded images (similar toAxes.imshow) as a plane in 3D.
Matplotlib does not have a native function for this. Below we build one by relyingonAxes3D.plot_surface. For simplicity, there are some differences toAxes.imshow: This function does not set the aspect of the Axes, hence pixels arenot necessarily square. Also, pixel edges are on integer values rather than pixelcenters. Furthermore, many optional parameters ofAxes.imshow are not implemented.
Multiple calls ofimshow3d use independent norms and thus different color scalesby default. If you want to have a single common color scale, you need to constructa suitable norm beforehand and pass it to allimshow3d calls.
A fundamental limitation of the 3D plotting engine is that intersecting objects cannotbe drawn correctly. One object will always be drawn after the other. Therefore,multiple image planes can well be used in the background as shown in this example.But this approach is not suitable if the planes intersect.
importmatplotlib.pyplotaspltimportnumpyasnpfrommatplotlib.colorsimportNormalizedefimshow3d(ax,array,value_direction='z',pos=0,norm=None,cmap=None):""" Display a 2D array as a color-coded 2D image embedded in 3d. The image will be in a plane perpendicular to the coordinate axis *value_direction*. Parameters ---------- ax : Axes3D The 3D Axes to plot into. array : 2D numpy array The image values. value_direction : {'x', 'y', 'z'} The axis normal to the image plane. pos : float The numeric value on the *value_direction* axis at which the image plane is located. norm : `~matplotlib.colors.Normalize`, default: Normalize The normalization method used to scale scalar data. See `imshow()`. cmap : str or `~matplotlib.colors.Colormap`, default: :rc:`image.cmap` The Colormap instance or registered colormap name used to map scalar data to colors. """ifnormisNone:norm=Normalize()colors=plt.get_cmap(cmap)(norm(array))ifvalue_direction=='x':nz,ny=array.shapezi,yi=np.mgrid[0:nz+1,0:ny+1]xi=np.full_like(yi,pos)elifvalue_direction=='y':nx,nz=array.shapexi,zi=np.mgrid[0:nx+1,0:nz+1]yi=np.full_like(zi,pos)elifvalue_direction=='z':ny,nx=array.shapeyi,xi=np.mgrid[0:ny+1,0:nx+1]zi=np.full_like(xi,pos)else:raiseValueError(f"Invalid value_direction:{value_direction!r}")ax.plot_surface(xi,yi,zi,rstride=1,cstride=1,facecolors=colors,shade=False)fig=plt.figure()ax=fig.add_subplot(projection='3d')ax.set(xlabel="x",ylabel="y",zlabel="z")nx,ny,nz=8,10,5data_xy=np.arange(ny*nx).reshape(ny,nx)+15*np.random.random((ny,nx))data_yz=np.arange(nz*ny).reshape(nz,ny)+10*np.random.random((nz,ny))data_zx=np.arange(nx*nz).reshape(nx,nz)+8*np.random.random((nx,nz))imshow3d(ax,data_xy)imshow3d(ax,data_yz,value_direction='x',cmap='magma')imshow3d(ax,data_zx,value_direction='y',pos=ny,cmap='plasma')plt.show()
Tags:plot-type: 3Dstyling: colormaplevel: advanced