pynbody.plot.sph.spherical_image

pynbody.plot.sph.spherical_image#

pynbody.plot.sph.spherical_image(sim, qty='rho', nside=None, kernel=None, threaded=None, units=None, weight=False, log=True, vmin=None, vmax=None, cmap=None, xsize=1600)[source]#

Make an SPH image on the sky around the origin.

Note

While pynbody does not require the healpy module to be installed, this function requires healpy to render the healpix image onto a Mollweide projection.

To install healpy, use pip install healpy.

Parameters:

  • sim (pynbody.snapshot.simsnap.SimSnap) – The simulation snapshot to plot. The output will be a projected spherical image centred on the origin of the particles in the snapshot.

  • qty (str | pynbody.array.SimArray) – The name of the array to interpolate. Default is ‘rho’, which gives a density image. Alternatively, an array can be passed in.

  • nside (int) – The healpix nside resolution to use (must be power of 2)

  • kernel (str, optional) – SPH kernel to use for smoothing; see create_kernel() for options.

  • units (str or pynbody.units.Unit, optional) – The units of the output. Default is None, in which case the units of the input quantity are used. Note that unless using weight, the output is a projected angular image. For example, for density, the output unit is mass per solid angle.

  • threaded (bool, optional) – If True, use threads to parallelise the rendering. (Default is set in the config file).

  • weight (bool or str, optional) – If True, the requested quantity is volume-averaged down the line of sight. If a string, the requested quantity is averaged down the line of sight weighted by the named array (e.g. use ‘rho’ for density-weighted quantity).

  • log (bool, optional) – If True, the image is log-scaled. (Default is True)

  • vmin (float, optional) – The minimum value for the color scale. If None, the minimum value of the image.

  • vmax (float, optional) – The maximum value for the color scale. If None, the maximum value of the image.

  • cmap (matplotlib.colors.Colormap or str, optional) – Colormap to use. If None, the default colormap is used.

  • xsize (int, optional) – The xsize parameter for healpy.mollview, which determines the resolution of the projection (i.e. does not affect the resolution of the actual image, but the presentation.) Default is 1600.