Combination

Author: PTHARRISH

Notes/itertools/combination.py

@@ -0,0 +1,39 @@
+# Combinations()
+# The combinations() function in Python, part of the itertools module,
+# is used to generate all possible combinations of a specified length from a given iterable
+# (like a list, string, or tuple).
+# Unlike permutations, where the order does matter,
+# combinations focus only on the selection of elements, meaning the order does not matter.
+# It returns an iterator producing tuples, each representing a unique combination of the input elements.
+
+
+# Example:
+from itertools import combinations
+
+a = "GeEK"
+# generate all combinations of length 2
+for j in combinations(a, 2):
+    print(j)
+
+# ('G', 'e')
+# ('G', 'E')
+# ('G', 'K')
+# ('e', 'E')
+# ('e', 'K')
+# ('E', 'K')
+
+
+# Explanation:
+# itertools.combinations()
+# generates all unordered pairs (length = 2) from the string "GeEK".
+# Each element is treated by its position and value.
+# The order within each tuple doesn't matter and no duplicate combinations (like ('e', 'G')) are included.
+
+# Syntax of Itertools.Combinations()
+# itertools.combinations(iterable, r)
+
+# Parameters:
+
+# iterable: The input sequence (list, string, tuple, etc.) from which combinations are formed.
+# r: The length of each combination to be generated.
+# Returns: An iterator that produces tuples, each representing a unique combination of r elements from the iterable, in the order they appear.

Notes/itertools/permutations.py

@@ -1,49 +1,52 @@
 # Itertools.permutation()
-# Itertools.permutation() function falls under the Combinatoric Generators. 
-# The recursive generators that are used to simplify combinatorial constructs such as permutations, combinations, 
+# Itertools.permutation() function falls under the Combinatoric Generators.
+# The recursive generators that are used to simplify combinatorial constructs such as permutations, combinations,
 # and Cartesian products are called combinatoric iterators
 
-# The word “Permutation” it refers to all the possible combinations in which a set or string can be ordered or arranged. 
-# Similarly here itertool.permutations() method provides us with all the possible arrangements 
-# that can be there for an iterator and all elements are assumed to be unique on the basis of their position 
-# and not by their value or category. 
+# The word “Permutation” it refers to all the possible combinations in which a set or string can be ordered or arranged.
+# Similarly here itertool.permutations() method provides us with all the possible arrangements
+# that can be there for an iterator and all elements are assumed to be unique on the basis of their position
+# and not by their value or category.
 
-# All these permutations are provided in lexicographical order. 
-# The function itertool.permutations() takes an iterator 
-# and ‘r’ (length of permutation needed) as input and 
-# assumes ‘r’ as default length of iterator 
-# if not mentioned and returns all possible permutations of length ‘r’ each. 
+# All these permutations are provided in lexicographical order.
+# The function itertool.permutations() takes an iterator
+# and ‘r’ (length of permutation needed) as input and
+# assumes ‘r’ as default length of iterator
+# if not mentioned and returns all possible permutations of length ‘r’ each.
 
 # Syntax:
 # Permutations(iterator, r)
 
 # Example:
-from itertools import permutations 
-name="HASH"
-p=permutations(name) # it return permutation object <itertools.permutations object at 0x000001DED0B63100>
+from itertools import permutations
+
+name = "HASH"
+p = permutations(
+    name
+)  # it return permutation object <itertools.permutations object at 0x000001DED0B63100>
 for i in list(p):
-    print(i) # print each value inside the permutation object
+    print(i)  # print each value inside the permutation object
 
 
 # Example:
-print ("All the permutations of the given list is:") 
-print (list(permutations([1, 'Spider'],2))) 
-print() 
+print("All the permutations of the given list is:")
+print(list(permutations([1, "Spider"], 2)))
+print()
 
 # All the permutations of the given list is:
 # [(1, 'Spider'), ('Spider', 1)]
- 
 
-print ("All the permutations of the given string is:") 
-print (list(permutations('PT'))) 
-print() 
+
+print("All the permutations of the given string is:")
+print(list(permutations("PT")))
+print()
 
 # All the permutations of the given string is:
 # [('P', 'T'), ('T', 'P')]
 
 
-print ("All the permutations of the given container is:") 
-print(list(permutations(range(3), 2)))  # 2 is r -> refers to the length or dimension 
+print("All the permutations of the given container is:")
+print(list(permutations(range(3), 2)))  # 2 is r -> refers to the length or dimension
 
 # If r and length is mentioned here the output is
 # All the permutations of the given container is (range(3), 2):
@@ -56,7 +59,7 @@
 
 # Example:
 
-lst=["a","b","c"]
+lst = ["a", "b", "c"]
 
 print("\nCombination of letters: ")
 for i in permutations(lst):