import numpy as np
from mejiro.utils import util
[docs]
def get_alpha(lens_model, kwargs_lens, scene_size, pixel_scale):
"""
Compute the deflection angle map for a given lens model over a 2D grid. The intended use case is:
.. code-block:: python
plt.quiver(*get_alpha(lens_model, kwargs_lens, scene_size, pixel_scale))
"""
xx, yy = util.build_meshgrid(scene_size, pixel_scale)
alpha_x, alpha_y = lens_model.alpha(xx.ravel(), yy.ravel(), kwargs_lens)
return xx, yy, alpha_x, alpha_y
[docs]
def get_potential(lens_model, kwargs_lens, scene_size, pixel_scale):
"""
Compute the potential map for a given lens model over a 2D grid. The scene size is calculated from overall scene size and pixel scale to match how scene size is calculated in the SyntheticImage class. This way, the same parameters will yield arrays with the same shapes and can be directly compared.
Parameters
----------
lens_model : object
See lenstronomy documentation.
kwargs_lens : list of dict
See lenstronomy documentation.
scene_size : float
The physical size of the scene in angular units (often, arcseconds).
pixel_scale : float
The size of each pixel.
Returns
-------
np.ndarray
A 2D array containing the potential values evaluated on a grid covering the scene.
"""
xx, yy = util.build_meshgrid(scene_size, pixel_scale)
return lens_model.potential(xx.ravel(), yy.ravel(), kwargs_lens).reshape(xx.shape)
[docs]
def get_kappa(lens_model, kwargs_lens, scene_size, pixel_scale):
"""
Compute the convergence (kappa) map for a given lens model over a 2D grid. The scene size is calculated from overall scene size and pixel scale to match how scene size is calculated in the SyntheticImage class. This way, the same parameters will yield arrays with the same shapes and can be directly compared.
Parameters
----------
lens_model : object
See lenstronomy documentation.
kwargs_lens : list of dict
See lenstronomy documentation.
scene_size : float
The physical size of the scene in angular units (often, arcseconds).
pixel_scale : float
The size of each pixel.
Returns
-------
np.ndarray
A 2D array containing the convergence (kappa) values evaluated on a grid covering the scene.
"""
xx, yy = util.build_meshgrid(scene_size, pixel_scale)
return lens_model.kappa(xx.ravel(), yy.ravel(), kwargs_lens).reshape(xx.shape)
[docs]
def get_subhalo_mass_function(realization, bins=10):
"""
Return the subhalo mass function from a pyHalo subhalo realization. The intended use case is quickly plotting the subhalo mass function in the following way:
.. code-block:: python
plt.loglog(*get_subhalo_mass_function(realization))
Parameters
----------
realization : object
A pyHalo realization.
bins : int, optional
Number of bins to use for the mass histogram (default is 10).
Returns
-------
bin_edges : numpy.ndarray
The edges of the mass bins (excluding the last edge), in the same units as the halo masses.
hist : numpy.ndarray
The number of halos in each mass bin.
"""
halo_masses = [halo.mass for halo in realization.halos if halo.is_subhalo]
log_mlow = np.floor(np.log10(np.min(halo_masses)))
log_mhigh = np.ceil(np.log10(np.max(halo_masses)))
hist, bin_edges = np.histogram(halo_masses, bins=np.logspace(log_mlow, log_mhigh, bins))
return bin_edges[0:-1], hist