Add device_utils.py

[python_utils.git] / list_utils.py

diff --git a/list_utils.py b/list_utils.py
index 533317eb6da71f44a4f8b3c338505c053c460c0b..05512b564c2303372ff81660840bfd29dcba942b 100644 (file)
--- a/list_utils.py
+++ b/list_utils.py
@@ -2,7 +2,7 @@
 
 from collections import Counter
 from itertools import islice
 
 from collections import Counter
 from itertools import islice

-from typing import Any, Iterator, List, Mapping
+from typing import Any, Iterator, List, Mapping, Sequence

 
 
 def shard(lst: List[Any], size: int) -> Iterator[Any]:
 
 
 def shard(lst: List[Any], size: int) -> Iterator[Any]:


@@ -48,6 +48,23 @@ def prepend(item: Any, lst: List[Any]) -> List[Any]:
     return lst
 
 
     return lst
 
 

+def remove_list_if_one_element(lst: List[Any]) -> Any:
+    """
+    Remove the list and return the 0th element iff its length is one.
+
+    >>> remove_list_if_one_element([1234])
+    1234
+
+    >>> remove_list_if_one_element([1, 2, 3, 4])
+    [1, 2, 3, 4]
+
+    """
+    if len(lst) == 1:
+        return lst[0]
+    else:
+        return lst
+
+

 def population_counts(lst: List[Any]) -> Mapping[Any, int]:
     """
     Return a population count mapping for the list (i.e. the keys are
 def population_counts(lst: List[Any]) -> Mapping[Any, int]:
     """
     Return a population count mapping for the list (i.e. the keys are


@@ -61,29 +78,126 @@ def population_counts(lst: List[Any]) -> Mapping[Any, int]:
     return Counter(lst)
 
 
     return Counter(lst)
 
 

-def most_common_item(lst: List[Any]) -> Any:
+def most_common(lst: List[Any], *, count=1) -> Any:

 
     """
     Return the most common item in the list.  In the case of ties,
     which most common item is returned will be random.
 
 
     """
     Return the most common item in the list.  In the case of ties,
     which most common item is returned will be random.
 

-    >>> most_common_item([1, 1, 1, 2, 2, 3, 3, 3, 3, 4, 4])
+    >>> most_common([1, 1, 1, 2, 2, 3, 3, 3, 3, 4, 4])

     3
 
     3
 

+    >>> most_common([1, 1, 1, 2, 2, 3, 3, 3, 3, 4, 4], count=2)
+    [3, 1]
+

     """
     """

-    return population_counts(lst).most_common(1)[0][0]
+    p = population_counts(lst)
+    return remove_list_if_one_element([_[0] for _ in p.most_common()[0:count]])

 
 
 
 

-def least_common_item(lst: List[Any]) -> Any:
+def least_common(lst: List[Any], *, count=1) -> Any:

     """
     Return the least common item in the list.  In the case of
     ties, which least common item is returned will be random.
 
     """
     Return the least common item in the list.  In the case of
     ties, which least common item is returned will be random.
 

-    >>> least_common_item([1, 1, 1, 2, 2, 3, 3, 3, 4])
+    >>> least_common([1, 1, 1, 2, 2, 3, 3, 3, 4])

     4
 
     4
 

+    >>> least_common([1, 1, 1, 2, 2, 3, 3, 3, 4], count=2)
+    [4, 2]
+
+    """
+    p = population_counts(lst)
+    mc = p.most_common()[-count:]
+    mc.reverse()
+    return remove_list_if_one_element([_[0] for _ in mc])
+
+
+def dedup_list(lst: List[Any]) -> List[Any]:
+    """
+    Remove duplicates from the list performantly.
+
+    >>> dedup_list([1, 2, 1, 3, 3, 4, 2, 3, 4, 5, 1])
+    [1, 2, 3, 4, 5]
+
+    """
+    return list(set(lst))
+
+
+def uniq(lst: List[Any]) -> List[Any]:
+    """
+    Alias for dedup_list.
+    """
+    return dedup_list(lst)
+
+
+def contains_duplicates(lst: List[Any]) -> bool:
+    """
+    Does the list contian duplicate elements or not?
+
+    >>> lst = [1, 2, 1, 3, 3, 4, 4, 5, 6, 1, 3, 4]
+    >>> contains_duplicates(lst)
+    True
+
+    >>> contains_duplicates(dedup_list(lst))
+    False
+
+    """
+    seen = set()
+    for _ in lst:
+        if _ in seen:
+            return True
+        seen.add(_)
+    return False
+
+
+def all_unique(lst: List[Any]) -> bool:
+    """
+    Inverted alias for contains_duplicates.
+    """
+    return not contains_duplicates(lst)
+
+
+def transpose(lst: List[Any]) -> List[Any]:
+    """
+    Transpose a list of lists.
+
+    >>> lst = [[1, 2], [3, 4], [5, 6]]
+    >>> transpose(lst)
+    [[1, 3, 5], [2, 4, 6]]
+
+    """
+    transposed = zip(*lst)
+    return [list(_) for _ in transposed]
+
+
+def ngrams(lst: Sequence[Any], n):
+    """
+    Return the ngrams in the sequence.
+
+    >>> seq = 'encyclopedia'
+    >>> for _ in ngrams(seq, 3):
+    ...     _
+    'enc'
+    'ncy'
+    'cyc'
+    'ycl'
+    'clo'
+    'lop'
+    'ope'
+    'ped'
+    'edi'
+    'dia'
+
+    >>> seq = ['this', 'is', 'an', 'awesome', 'test']
+    >>> for _ in ngrams(seq, 3):
+    ...     _
+    ['this', 'is', 'an']
+    ['is', 'an', 'awesome']
+    ['an', 'awesome', 'test']

     """
     """

-    return population_counts(lst).most_common()[-1][0]
+    for i in range(len(lst) - n + 1):
+        yield lst[i:i + n]

 
 
 if __name__ == '__main__':
 
 
 if __name__ == '__main__':