Given a list containing all the element and second list of tuple depicting the relation between indices, the task is to output a dictionary showing the relation of every element from the first list to every other element in the list.
These type of problems are often encountered in Coding competition.
Below are some ways to achieve the above task.
Input: indices = ['x','y','z','w','t','r'] relation =[('x', 'y'), ('x', 'z'), ('x', 'w'), ('y', 'z'), ('y', 'w'), ('z', 'w')] Output: {'x': ['y', 'z', 'w'], 'y': ['x', 'z', 'w'], 'z': ['x', 'y', 'w'], 'w': ['x', 'y', 'z'], 't': [], 'r': []}
Method #1: Using iteration is the easiest way to solve any task
#Python code to convert list of tuple into dictionary showing #relation of every element from first list to every other element in the list. #List initialization indices = [ 'x' , 'y' , 'z' , 'w' , 't' , 'r' ] relation = [( 'x' , 'y' ), ( 'x' , 'z' ), ( 'x' , 'w' ), ( 'y' , 'z' ), ( 'y' , 'w' ), ( 'z' , 'w' )] #dictionary initialization Output = {} #Iteration for elem in indices: temp = [] for rel in relation: if elem in rel: if elem = = rel[ 0 ]: temp.append(rel[ 1 ]) else : temp.append(rel[ 0 ]) Output[elem] = temp temp = [] print ( "Initial list of tuple is :" ) print (relation) print ( "Converted dictionary of list :" ) print (Output) |
Output : Initial list of tuple is : [('x', 'y'), ('x', 'z'), ('x', 'w'), ('y', 'z'), ('y', 'w'), ('z', 'w')] Converted dictionary of list : {'w': ['x', 'y', 'z'], 'r': [], 'x': ['y', 'z', 'w'], 't': [], 'y': ['x', 'z', 'w'], 'z': ['x', 'y', 'w']}
Method #2: Using networkx is the most simplest and shortest
way to convert list of tuple into dictionary
#Python code to convert list of tuple into dictionary showing #relation of every element from first list to every other element in the list. #Importing import networkx as nx #List initialization indices = [ 'x' , 'y' , 'z' , 'w' , 't' , 'r' ] relation = [( 'x' , 'y' ), ( 'x' , 'z' ), ( 'x' , 'w' ), ( 'y' , 'z' ), ( 'y' , 'w' ), ( 'z' , 'w' )] #dictionary initialization Output = {} #Using networkx to solve temp = nx.Graph(relation) temp.add_nodes_from(indices) Output = nx.to_dict_of_lists(temp) #Printing print ( "Initial list of tuple is :" ) print (relation) print ( "Converted dictionary of list :" ) print (Output) |
Output : Initial list of tuple is : [('x', 'y'), ('x', 'z'), ('x', 'w'), ('y', 'z'), ('y', 'w'), ('z', 'w')] Converted dictionary of list : {'w': ['x', 'y', 'z'], 'r': [], 'x': ['y', 'z', 'w'], 't': [], 'y': ['x', 'z', 'w'], 'z': ['x', 'y', 'w']}
Method #3: Using itertools and groupby is another way to convert list of tuple into dictionary.
#Python code to convert list of tuple into dictionary showing #relation of every element from first list to every other element in the list. #Importing from itertools import groupby from operator import itemgetter #List initialization indices = [ 'x' , 'y' , 'z' , 'w' , 't' , 'r' ] relation = [( 'x' , 'y' ), ( 'x' , 'z' ), ( 'x' , 'w' ), ( 'y' , 'z' ), ( 'y' , 'w' ), ( 'z' , 'w' )] #Using itertools.groupby and maps edge = relation + [ tuple ( reversed (pair)) for pair in relation] st = itemgetter( 0 ) end = itemgetter( 1 ) groups = groupby( sorted (edge), key = st) mapping = {vertex: list ( map (end, edges)) for vertex, edges in groups} from collections import defaultdict #Output list Output = defaultdict( list , mapping) Output = dict (mapping) Output.update({vertex: [] for vertex in indices if vertex not in mapping}) #Printing print ( "Initial list of tuple is :" ) print (relation) print ( "Converted dictionary of list :" ) print (Output) |
Output : Initial list of tuple is : [('x', 'y'), ('x', 'z'), ('x', 'w'), ('y', 'z'), ('y', 'w'), ('z', 'w')] Converted dictionary of list : {'w': ['x', 'y', 'z'], 'r': [], 'x': ['y', 'z', 'w'], 't': [], 'y': ['x', 'z', 'w'], 'z': ['x', 'y', 'w']}
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