PickList
PickList[list, sel]⟹filteredList
finds those elements of list for which the corresponding element of sel is True and returns a list of those elements.
PickList[list, sel, pattern]⟹filteredList
finds those elements of list for which the corresponding element of sel matches pattern, and returns a list of those elements.
Details
- PickList behaves similarly to the Mathematica function Pick, except for in the following cases, where Pick can behave in unusual ways:
- If list = {a, b, f[b]} and sel = {1, Cos[1], Sin[1]}, that Pick[list, sel, 1] returns {a, f[b]} because it works on sequences regardless of their head. PickList works only on the list level so, PickList[list, sel, 1] will return {a}.
- PickList matches only on lists and not sequences, and thus will not function at multiple depths or with arbitrary sequences.
- PickList does not work with SparseArrays as Pick does.
- PickList is substantially slower than Pick in the case of very large lists of inputs.
-
MismatchedListLength Expressions `1` and `2` have incompatible shapes.
Input
Output
Messages
Examples
Basic Examples (5)
PickList out only those elements whenever a 1 appears in the "selector" list:
PickList out only those elements where the "selector" list is True:
PickList out only those elements where the "selector" list matches the pattern:
PickList out only those elements where the "selector" list matches the pattern, where the pattern is more complex:
PickList out only those elements whose parts match the pattern:
Additional Examples (10)
In cases where items in the list and sel have explicit heads, PickList looks only at the list level:
In cases where items in the list and sel have explicit heads, Pick looks at the sequence level:
Pick is substantially faster than Pick when working with very large lists:
PickList is substantially slower than Pick when working with very large lists:
Unlike PickList, Pick does accept sparse arrays as selectors:
Unlike PickList, Pick works at greater levels of depth in the expression:
Unlike PickList, Pick works on arbitrary sequences:
Unlike Pick, PickList does not accept sparse arrays as selectors:
Unlike Pick, PickList does works only on the first level of the list:
Unlike Pick, PickList only works on lists and not arbitrary sequences:
