Arbor.add_alias_field(alias, field, units=None, force_add=True)[source]

Add a field as an alias to another field.

  • alias (string) – Alias name.
  • field (string) – The field to be aliased.
  • units (optional, string) – Units in which the field will be returned.
  • force_add (optional, bool) – If True, add field even if it already exists and warn the user and raise an exception if dependencies do not exist. If False, silently do nothing in both instances. Default: True.


>>> import ytree
>>> a = ytree.load("tree_0_0_0.dat")
>>> # "Mvir" exists on disk
>>> a.add_alias_field("mass", "Mvir", units="Msun")
>>> print (a["mass"])