def _find_suggestions(self):
from yt.funcs import levenshtein_distance
field = self.field
ds = self.ds
suggestions = {}
if not isinstance(field, tuple):
ftype, fname = None, field
elif field[1] is None:
ftype, fname = None, field[0]
else:
ftype, fname = field
# Limit the suggestions to a distance of 3 (at most 3 edits)
# This is very arbitrary, but is picked so that...
# - small typos lead to meaningful suggestions (e.g. `densty` -> `density`)
# - we don't suggest unrelated things (e.g. `pressure` -> `density` has a distance
# of 6, we definitely do not want it)
# A threshold of 3 seems like a good middle point.
max_distance = 3
# Suggest (ftype, fname), with alternative ftype
for ft, fn in ds.derived_field_list:
if fn.lower() == fname.lower() and (ftype is None or
ft.lower() != ftype.lower()):
suggestions[ft, fn] = 0
if ftype is not None:
# Suggest close matches using levenshtein distance
fields_str = {_: str(_).lower() for _ in ds.derived_field_list}
field_str = str(field).lower()
for (ft, fn), fs in fields_str.items():
distance = levenshtein_distance(field_str,
fs,
max_dist=max_distance)
if distance < max_distance:
if (ft, fn) in suggestions:
continue
suggestions[ft, fn] = distance
# Return suggestions sorted by increasing distance (first are most likely)
self.suggestions = [(ft, fn) for (
ft,
fn), distance in sorted(suggestions.items(), key=lambda v: v[1])]
def test_levenshtein():
assert_equal(levenshtein_distance("abcdef", "abcdef"), 0)
# Deletions / additions
assert_equal(levenshtein_distance("abcdef", "abcde"), 1)
assert_equal(levenshtein_distance("abcdef", "abcd"), 2)
assert_equal(levenshtein_distance("abcdef", "abc"), 3)
assert_equal(levenshtein_distance("abcdf", "abcdef"), 1)
assert_equal(levenshtein_distance("cdef", "abcdef"), 2)
assert_equal(levenshtein_distance("bde", "abcdef"), 3)
# Substitutions
assert_equal(levenshtein_distance("abcd", "abc_"), 1)
assert_equal(levenshtein_distance("abcd", "ab__"), 2)
assert_equal(levenshtein_distance("abcd", "a___"), 3)
assert_equal(levenshtein_distance("abcd", "____"), 4)
# Deletion + Substitutions
assert_equal(levenshtein_distance("abcd", "abc_z"), 2)
assert_equal(levenshtein_distance("abcd", "ab__zz"), 4)
assert_equal(levenshtein_distance("abcd", "a___zzz"), 6)
assert_equal(levenshtein_distance("abcd", "____zzzz"), 8)
# Max distance
assert_equal(levenshtein_distance("abcd", "", max_dist=0), 1)
assert_equal(levenshtein_distance("abcd", "", max_dist=3), 4)
assert_equal(levenshtein_distance("abcd", "", max_dist=10), 4)
assert_equal(levenshtein_distance("abcd", "", max_dist=1), 2)
assert_equal(levenshtein_distance("abcd", "a", max_dist=2), 3)
assert_equal(levenshtein_distance("abcd", "ad", max_dist=2), 2)
assert_equal(levenshtein_distance("abcd", "abd", max_dist=2), 1)
assert_equal(levenshtein_distance("abcd", "abcd", max_dist=2), 0)