Manipulating dict¶
Let us understand how we can manipulate the dicts in Python.* We can add new key value pairs to dict by using typical assignment.
- We can also use assignment operation to update existing key value pair in the
dict. setdefaultcan be used to get the element from thedictby using key. If key does not exist, it will update thedictwith the key passed along with default value.updatecan be used to merge a list of pairs (2 tuples) or adictinto thedict.- Elements from the dict can be removed using functions like
popandpopitem.popis typically used to remove the element using key.popitemis used to remove one of the item (typically last) from thedict.
In [1]:
d = {'id': 1, 'first_name': 'Scott', 'last_name': 'Tiger', 'amount': 1000.0}
In [2]:
d['commission_pct'] = 10 # Adding Element
In [3]:
d['phone_numbers'] = 1234567890
In [4]:
d
Out[4]:
{'id': 1,
'first_name': 'Scott',
'last_name': 'Tiger',
'amount': 1000.0,
'commission_pct': 10,
'phone_numbers': 1234567890}
In [5]:
d['amount'] = 1500.0
In [6]:
d
Out[6]:
{'id': 1,
'first_name': 'Scott',
'last_name': 'Tiger',
'amount': 1500.0,
'commission_pct': 10,
'phone_numbers': 1234567890}
In [7]:
d = {'id': 1, 'first_name': 'Scott', 'last_name': 'Tiger', 'amount': 1000.0}
In [8]:
d.setdefault?
Signature: d.setdefault(key, default=None, /) Docstring: Insert key with a value of default if key is not in the dictionary. Return the value for key if key is in the dictionary, else default. Type: builtin_function_or_method
In [9]:
d.setdefault('amount')
Out[9]:
1000.0
In [10]:
d.setdefault('commission_pct')
In [11]:
d
Out[11]:
{'id': 1,
'first_name': 'Scott',
'last_name': 'Tiger',
'amount': 1000.0,
'commission_pct': None}
In [12]:
d = {'id': 1, 'first_name': 'Scott', 'last_name': 'Tiger', 'amount': 1000.0}
In [13]:
d
Out[13]:
{'id': 1, 'first_name': 'Scott', 'last_name': 'Tiger', 'amount': 1000.0}
In [14]:
d.setdefault('commission_pct', 0)
Out[14]:
0
In [15]:
d
Out[15]:
{'id': 1,
'first_name': 'Scott',
'last_name': 'Tiger',
'amount': 1000.0,
'commission_pct': 0}
In [16]:
d.setdefault('commission_pct', 100)
Out[16]:
0
In [17]:
d
Out[17]:
{'id': 1,
'first_name': 'Scott',
'last_name': 'Tiger',
'amount': 1000.0,
'commission_pct': 0}
In [18]:
d.update?
Docstring: D.update([E, ]**F) -> None. Update D from dict/iterable E and F. If E is present and has a .keys() method, then does: for k in E: D[k] = E[k] If E is present and lacks a .keys() method, then does: for k, v in E: D[k] = v In either case, this is followed by: for k in F: D[k] = F[k] Type: builtin_function_or_method
In [19]:
d = {'id': 1}
In [20]:
d
Out[20]:
{'id': 1}
In [21]:
d.update({'first_name': 'Donald', 'last_name': 'Duck'})
In [22]:
d
Out[22]:
{'id': 1, 'first_name': 'Donald', 'last_name': 'Duck'}
In [23]:
d.update([('amount', 1000.0), ('commission_pct', 10)])
In [24]:
d
Out[24]:
{'id': 1,
'first_name': 'Donald',
'last_name': 'Duck',
'amount': 1000.0,
'commission_pct': 10}
In [25]:
d.update([('amount', 1500.0), ('commission_pct', 5), ('phone_numbers', 1234567890)])
In [26]:
d
Out[26]:
{'id': 1,
'first_name': 'Donald',
'last_name': 'Duck',
'amount': 1500.0,
'commission_pct': 5,
'phone_numbers': 1234567890}
In [27]:
d = {'id': 1, 'first_name': 'Scott', 'last_name': 'Tiger', 'amount': 1000.0}
In [28]:
d['commission_pct'] = 10 # Adding Element
In [29]:
d['phone_numbers'] = 1234567890
In [30]:
d
Out[30]:
{'id': 1,
'first_name': 'Scott',
'last_name': 'Tiger',
'amount': 1000.0,
'commission_pct': 10,
'phone_numbers': 1234567890}
In [31]:
d.pop('phone_numbers')
Out[31]:
1234567890
In [32]:
d
Out[32]:
{'id': 1,
'first_name': 'Scott',
'last_name': 'Tiger',
'amount': 1000.0,
'commission_pct': 10}
In [33]:
d.pop('phone_numbers') # throws KeyError
--------------------------------------------------------------------------- KeyError Traceback (most recent call last) Input In [33], in <cell line: 1>() ----> 1 d.pop('phone_numbers') KeyError: 'phone_numbers'
In [34]:
d.pop('phone_numbers', 'No such key exists')
Out[34]:
'No such key exists'
In [35]:
d.pop?
Docstring: D.pop(k[,d]) -> v, remove specified key and return the corresponding value. If key is not found, d is returned if given, otherwise KeyError is raised Type: builtin_function_or_method
In [36]:
d
Out[36]:
{'id': 1,
'first_name': 'Scott',
'last_name': 'Tiger',
'amount': 1000.0,
'commission_pct': 10}
In [37]:
d.popitem?
Signature: d.popitem() Docstring: Remove and return a (key, value) pair as a 2-tuple. Pairs are returned in LIFO (last-in, first-out) order. Raises KeyError if the dict is empty. Type: builtin_function_or_method
In [38]:
d.popitem()
Out[38]:
('commission_pct', 10)
In [39]:
d
Out[39]:
{'id': 1, 'first_name': 'Scott', 'last_name': 'Tiger', 'amount': 1000.0}