how to get key and value from dictionary in python code example

Example 1: how to get the key for a value in a dictionary in python

# function to return key for any value 
def get_key(val): 
    for key, value in my_dict.items(): 
         if val == value: 
             return key 
  
    return "key doesn't exist"
  
# Driver Code 
  
my_dict ={"java":100, "python":112, "c":11} 
  
print(get_key(100)) 
print(get_key(11))

Example 2: how to get key of a particular value in dictionary python using index

mydict = {'george': 16, 'amber': 19}
print(list(mydict.keys())[list(mydict.values()).index(16)])  # Prints george

Example 3: python get value from dictionary

dict = {'color': 'blue', 'shape': 'square', 'perimeter':20}
dict.get('shape') #returns square

#You can also set a return value in case key doesn't exist (default is None)
dict.get('volume', 'The key was not found') #returns 'The key was not found'

Example 4: python dictionary access value by key

# Create a list of dictionary
datadict = [{'Name': 'John', 'Age': 38, 'City': 'Boston'},
 {'Name': 'Sara', 'Age': 47, 'City': 'Charlotte'},
 {'Name': 'Peter', 'Age': 63, 'City': 'London'},
 {'Name': 'Cecilia', 'Age': 28, 'City': 'Memphis'}]

# Build a function to access to list of dictionary
def getDictVal(listofdic, name, retrieve):
    for item in listofdic:
        if item.get('Name')==name:
            return item.get(retrieve)
          
 # Use the 'getDictVal' to read the data item
getDictVal(datadict, 'Sara', 'City') # Return 'Charlotte'

# -------------------
# to convert a dataframe to data dictionary
df = pd.DataFrame({'Name': ['John', 'Sara','Peter','Cecilia'],
                   'Age': [38, 47,63,28],
                  'City':['Boston', 'Charlotte','London','Memphis']})

datadict = df.to_dict('records')

Example 5: find key by value python

print(list(d.keys())[list(d.values()).index(990)])