[Yt-svn] yt: Updating docstrings to HaloFinding.
hg at spacepope.org
hg at spacepope.org
Fri Jun 25 21:02:39 PDT 2010
hg Repository: yt
details: yt/rev/6d83469df13f
changeset: 1823:6d83469df13f
user: Stephen Skory <stephenskory at yahoo.com>
date:
Fri Jun 25 21:02:09 2010 -0700
description:
Updating docstrings to HaloFinding.
diffstat:
yt/lagos/HaloFinding.py | 39 +++++++++++++++++++++++++++++++++++++++
1 files changed, 39 insertions(+), 0 deletions(-)
diffs (63 lines):
diff -r 6e22d1c3f9b0 -r 6d83469df13f yt/lagos/HaloFinding.py
--- a/yt/lagos/HaloFinding.py Fri Jun 25 16:43:54 2010 -0700
+++ b/yt/lagos/HaloFinding.py Fri Jun 25 21:02:09 2010 -0700
@@ -1464,6 +1464,22 @@
fancy_padding=True, safety=1.5, premerge=True, sample=0.03):
r"""Parallel HOP halo finder.
+ Halos are built by:
+ 1. Calculating a density for each particle based on a smoothing kernel.
+ 2. Recursively linking particles to other particles from lower density
+ particles to higher.
+ 3. Geometrically proximate chains are identified and
+ 4. merged into final halos following merging rules.
+
+ Lower thresholds generally produce more halos, and the largest halos
+ become larger. Also, halos become more filamentary and over-connected.
+
+ This is very similar to HOP, but it does not produce precisely the
+ same halos due to unavoidable numerical differences.
+
+ Skory et al. "Parallel HOP: A Scalable Halo Finder for Massive
+ Cosmological Data Sets." arXiv (2010) 1001.3411
+
Parameters
----------
pf : EnzoStaticOutput object
@@ -1708,6 +1724,19 @@
def __init__(self, pf, threshold=160, dm_only=True, padding=0.02):
r"""HOP halo finder.
+ Halos are built by:
+ 1. Calculating a density for each particle based on a smoothing kernel.
+ 2. Recursively linking particles to other particles from lower density
+ particles to higher.
+ 3. Geometrically proximate chains are identified and
+ 4. merged into final halos following merging rules.
+
+ Lower thresholds generally produce more halos, and the largest halos
+ become larger. Also, halos become more filamentary and over-connected.
+
+ Eisenstein and Hut. "HOP: A New Group-Finding Algorithm for N-Body
+ Simulations." ApJ (1998) vol. 498 pp. 137-142
+
Parameters
----------
pf : EnzoStaticOutput object
@@ -1760,6 +1789,16 @@
def __init__(self, pf, link=0.2, dm_only=True, padding=0.02):
r"""Friends-of-friends halo finder.
+ Halos are found by linking together all pairs of particles closer than
+ some distance from each other. Particles may have multiple links,
+ and halos are found by recursively linking together all such pairs.
+
+ Larger linking lengths produce more halos, and the largest halos
+ become larger. Also, halos become more filamentary and over-connected.
+
+ Davis et al. "The evolution of large-scale structure in a universe
+ dominated by cold dark matter." ApJ (1985) vol. 292 pp. 371-394
+
Parameters
----------
pf : EnzoStaticOutput object
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