Plotting

Explore how to plot neurons in 2d using and in 3d

Plotting

navis lets you plot neurons in 2d using matplotlib (nice for figures), and in 3d using either plotly when in a notebook environment like Deepnote or using a vispy-based 3D viewer when using a Python terminal. The vispy solution won’t work in Deepnote so we will focus on matplotlib’s 2d and plotly for 3d.

import navis

# This is relevant because Deepnote does not (yet) support fancy progress bars
navis.set_pbars(jupyter=False)

# Load one of the example neurons shipped with navis
n = navis.example_neurons(1, kind='skeleton')

WARNING: Could not load OpenGL library.

# Make a 2d plot 
fig, ax = navis.plot2d(n)

# Note that this is equivalent to 
# fig, ax = n.plot2d()

png

If you have seen an olfactory projection neuron before, you might have noticed that this neuron is upside-down. That’s because hemibrain neurons have an odd orienation in that the anterior-posterior axis not the z- but the y-axis (they have been image from above).

For us that just means we have to turn the camera ourselves if we want a frontal view:

# Make a 2d plot 
fig, ax = navis.plot2d(n)

# Change camera (azimuth + elevation)
ax.azim, ax.elev = -90, -90

png

Let’s do the same in 3d:

# Get a list of neurons
nl = navis.example_neurons(5)

# Plot
navis.plot3d(nl, width=1000)

Navigation:

  • left click and drag to rotate (select “Orbital rotation” above the legend to make your life easier)
  • mousewheel to zoom
  • middle-mouse + drag to translate
  • click legend items (single or double) to hide/unhide

Above plots are very basic examples but there are a ton of ways to tweak things to your liking. For a full list of parameters check out the docs for plot2d and plot3d.

Let’s for example change the colors. In general, colors can be:

  • a string - e.g. "red" or just "r"
  • an rgb/rgba tuple - e.g. (1, 0, 0) for red
# Plot all neurons in red
fig, ax = navis.plot2d(n, color='r')
ax.azim, ax.elev = -90, -90

png

# Plot all neurons in red (color as tuple)
fig, ax = navis.plot2d(n, color=(1, 0, 0, 1))
ax.azim, ax.elev = -90, -90

png

When plotting multiple neurons you can either use:

  • a single color ("r" or (1, 0, 0)) -> assigned to all neurons
  • a list of colors (['r', 'yellow', (0, 0, 1)]) with a color for each neuron
  • a dictionary mapping neuron IDs to colors ({1734350788: 'r', 1734350908: (1, 0, 1)})
  • the name of a matplotlib or seaborn color palette
# Plot with a specific color palette
navis.plot3d(nl, color='jet')