Common Helper Functions

The pyTooling.Common package contains several useful helper functions, which are explained in the following sections.

getsizeof

The getsizeof() functions returns the “true” size of a Python object including auxiliary data structures.

Example:

class A:
  _data : int

  def __init__(self) -> None:
    _data = 5

from pyTooling.Common import getsizeof
a = A()
print(getsizeof(a))

Details

In addition to sys.getsizeof(), the used algorithm accounts also for:

• __dict__

• __slots__

• iterable members made of:

  • tuple

  • list

  • typing.Set

  • collection.deque

Background Information

The function sys.getsizeof() only returns the raw size of a Python object and doesn’t account for the overhead of e.g. _dict__ to store dynamically allocated object members.

isnestedclass

The isnestedclass() functions returns true, if a class is a nested class inside another class.

Example:

class A:
  class N:
    _data : int

    def __init__(self) -> None:
      _data = 5

N = A.N
print(isnestedclass(N, A))

firstElement

firstElement() returns the first element from an iterable.

lst = [1, 2, 3]

f = firstElement(lst)
# 1

lastElement

lastElement() returns the last element from an iterable.

lst = [1, 2, 3]

l = lastElement(lst)
# 3

firstItem

firstItem() returns the first item from an iterable.

lst = [1, 2, 3]

f = firstItem(lst)
# 1

lastItem

lastItem() returns the last item from an iterable.

lst = [1, 2, 3]

l = lastItem(lst)
# 3

firstKey

firstKey() returns the first key from a dictionary.

d = {}
d["a"] = 1
d["b"] = 2

k = firstKey(d)
# "a"

Hint

The dictionary should be an order preserving dictionary, otherwise the “first” item is not defined and can return any key.

firstValue

firstValue() returns the first value from a dictionary.

d = {}
d["a"] = 1
d["b"] = 2

k = firstValue(d)
# 1

Hint

The dictionary should be an order preserving dictionary, otherwise the “first” item is not defined and can return any value.

firstPair

firstPair() returns the first pair (key-value-pair tuple) from a dictionary.

d = {}
d["a"] = 1
d["b"] = 2

k = firstPair(d)
# ("a", 1)

Hint

The dictionary should be an order preserving dictionary, otherwise the “first” item is not defined and can return any pair.

mergedicts

mergedicts() merges multiple dictionaries into a new single dictionary. It accepts an arbitrary number of dictionaries to merge. Optionally, the named parameter func accepts a function that can be applied to every element during the merge operation.

Example:

dictA = {11: "11", 12: "12", 13: "13"}
dictB = {21: "21", 22: "22", 23: "23"}

mergedDict = mergedicts(dictA, dictB)
# {11: "11", 12: "12", 13: "13", 21: "21", 22: "22", 23: "23"}

zipdicts

zipdicts() is a generator that iterates multiple dictionaries simultaneously. It expects multiple dictionary objects (fulfilling the mapping protocol) as positional parameters.

An exception is raised, if not all dictionary objects have the same number of items. Also an exception is raised, if a key doesn’t exist in all dictionaries.

Example:

dictA = {11: "11", 12: "12", 13: "13"}
dictB = {11: "21", 12: "22", 13: "23"}

for key, valueA, valueB in zipdicts(dictA, dictB):
  pass