Merge pull request #4 from suman2826/master

soum-sr · web-flow · commit 8340adeaf9a8 · 2020-10-25T20:55:28.000+05:30
added defaultdict library
diff --git a/Collections/default_dict_basic.py b/Collections/default_dict_basic.py
@@ -0,0 +1,39 @@
+#It is a subclass of the dict class that returns a dictionary like-object.
+#The functionality of both dictionaries and defaultdict are almost same except it never raises a keyerror it provides the deafult value for the key that doesnot exixts.
+from collections import defaultdict
+def value():
+	return "No"
+
+d1 = defaultdict(value)
+d1["deafult"] = 1
+d1["dict"] = 2
+print(d1["deafult"])  # 1
+print(d1["dict"])  # 2
+print(d1["defaultdict"]) # No
+
+#instead of writing it in function we can use lambda parameter
+d2 = defaultdict(lambda:"No")
+d1["deafult"] = 1
+d1["dict"] = 2
+print(d1["deafult"])  # 1
+print(d1["dict"])  # 2
+print(d1["defaultdict"]) # No
+
+#using list as default factory
+#when the list class is passed as the argument then a default divt is created with the values that are list
+d3 = defaultdict(list)
+for i in range(5):
+	d3[i].append(i)
+print(d3)  #{0: [0], 1: [1], 2: [2], 3: [3], 4: [4]})
+
+#using int as default factory
+#when the int class is passed then a defaultdict is created with default as zero.
+d4 = defaultdict(int)
+nums = [1,2,3,4,1,4,3,5]
+for num in nums:
+	d4[i] += 1
+print(d4)  #{1: 2, 2: 1, 3: 2, 4: 2, 5: 1})
+
+
+
+
