# Initialising list of dictionary
ini_dict = [{'a':5, 'b':10, 'c':90},
         {'a':45, 'b':78},
         {'a':90, 'c':10}]

# printing initial dictionary
print ("initial dictionary", (ini_dict))

# sum the values with same keys
result = {}
for d in ini_dict:
   for k in d.keys():
      result[k] = result.get(k,0)   d[k]


print("resultant dictionary : ", (result))

Can someone explain the program line by line

CodePudding user response：

Creating a list of dictionary's

ini_dict = [{'a':5, 'b':10, 'c':90},
     {'a':45, 'b':78},
     {'a':90, 'c':10}]

Prints out the list with dictionary's

print ("initial dictionary", (ini_dict))

Creates a new dictionary

result = {}

Loop's through the List of dictionarys

 for d in ini_dict:

so the first d would be {'a':5, 'b':10, 'c':90}

Loop's through the keys of that dict

for k in d.keys():

-> a, b and c

Creates or gets the same key in the result dict and adds the value from the current key. Default value for a new created key is 0.

result[k] = result.get(k,0)   d[k]

Prints out the result dict

print("resultant dictionary : ", (result))

CodePudding user response：

the first line initialises a list of three dictionaries.

ini_dict = [{'a':5,  'b':10, 'c':90},
            {'a':45, 'b':78},
            {'a':90,         'c':10}]

next up, the dictionary is printed

print ("initial dictionary", (ini_dict))

finally, a weighted histogram is made of the dictionaries based on the keys of the elements within said dictionaries. This is done in three steps:

1. iterating over the list of dictionaries to get at each different dictionary.

   for d in ini_dict:

remember: ini_dict is a list of dictionaries. when you for-loop over a list, the symbol (here d) becomes each of the dictionaries.

2. iterating over the keys in the dictionary. The method dict.keys() returns a list of keys, over which can be iterated.

   for k in d.keys():

3. finally, for each key in the dictionary the corresponding key in the result dictionary is modified to add the new value. with result.get(k,0) the value for the key k in the result dictionary is fetched, but 0 is the default value if the key is not present.

   result[k] = result.get(k,0) d[k]

This just replaces the result with the previous result the value in d.

At the end of this bit of code, the result dictionary has the added value of each of the keys.