prefsort 0.1.0

Sort a sequence, preferring some values

Partially sort a sequence, preferring some values.

from prefsort import prefsorted

seq = list('abcde')

seq2 = prefsorted(seq, 'c b')
assert seq2 == ['c', 'b', 'a', 'd', 'e']

Note that this doesn’t sort the majority of the sequence in the way Python’s normal list.sort() or sorted() do. It just pulls the preferred members to the front of the list.

This is particularly handy to have when organizing data columns, for example with pandas, the following will make sure the id and name columns come first in a DataFrame:

df = df.reindex(columns=prefsorted(df.columns, 'id name'))

There is also a reverse parameter that will put the “preferred” items at the end of the list. In this case it’s a “negative preference.”

seq2 = prefsorted(seq, 'c b', reverse=True)
assert seq2 == ['a', 'd', 'e', 'c', 'b']