The method update() adds dictionary dict2's key-values pairs in to dict. This function does not return anything.,dict2 − This is the dictionary to be added into dict.,This method does not return any value.,Following is the syntax for update() method −
Following is the syntax for update() method −
dict.update(dict2)
#!/usr/bin/python3
dict = {
'Name': 'Zara',
'Age': 7
}
dict2 = {
'Sex': 'female'
}
dict.update(dict2)
print("updated dict : ", dict)When we run above program, it produces the following result −
updated dict: {
'Sex': 'female',
'Age': 7,
'Name': 'Zara'
}Because dict1.update(dict2) update the value of dict1 with the values of dict2 but do not returns anything (hence printing None in your case). In order to see the updated values, you need to do:
students.update(student1) print(students)
The update method merges the dicts in-place and returns 'None', which is what you're printing. You need to print students itself.
students = {
'dsd': 13
}
student1 = {
'dsdsd': 15
}
students.update(student1)
print(students)Last Updated : 04 Oct, 2021,GATE CS 2021 Syllabus
Output:
Original Dictionary: {
'A': 'Geeks',
'B': 'For'
}
Dictionary after updation: {
'A': 'Geeks',
'B': 'Geeks'
}Output:
Key exist, value updated = 600 {
'm': 600,
'n': 100,
't': 500
}update() method updates the dictionary with elements from a dictionary object or an iterable object of key/value pairs.,The update() method updates the dictionary with the elements from another dictionary object or from an iterable of key/value pairs.,The update() method takes either a dictionary or an iterable object of key/value pairs (generally tuples).,Note: The update() method adds element(s) to the dictionary if the key is not in the dictionary. If the key is in the dictionary, it updates the key with the new value.
Example
marks = {
'Physics': 67,
'Maths': 87
}
internal_marks = {
'Practical': 48
}
marks.update(internal_marks)
print(marks)
# Output: {
'Physics': 67,
'Maths': 87,
'Practical': 48
}Example
marks = {
'Physics': 67,
'Maths': 87
}
internal_marks = {
'Practical': 48
}
marks.update(internal_marks)
print(marks)
# Output: {
'Physics': 67,
'Maths': 87,
'Practical': 48
}The syntax of update() is:
dict.update([other])Example 1: Working of update()
d = {
1: "one",
2: "three"
}
d1 = {
2: "two"
}
# updates the value of key 2
d.update(d1)
print(d)
d1 = {
3: "three"
}
# adds element with key 3
d.update(d1)
print(d)Example 2: update() When Tuple is Passed
dictionary = {
'x': 2
}
dictionary.update([('y', 3), ('z', 0)])
print(dictionary)Update the dictionary with the key/value pairs from other, overwriting existing keys. Return None.,update() accepts either another dictionary object or an iterable of key/value pairs (as tuples or other iterables of length two). If keyword arguments are specified, the dictionary is then updated with those key/value pairs: d.update(red=1, blue=2).,Counters can also be initialized directly with count information from another count dictionary or with keyword argumemnts:,If key is in the dictionary, remove it and return its value, else return default. If default is not given and key is not in the dictionary, a KeyError is raised.
1 >>> enron_network
2
3 {
'Mike Grigsby': ['Louise Kitchen', 'Scott Neal', 'Kenneth Lay'],
4 'Greg Whalley': ['Mike Grigsby', 'Louise Kitchen'],
5
6
}>>> X = {
'x': 42,
'y': 3.14,
'z': 7
} >>>
Y = {
1: 2,
3: 4
} >>>
Z = {}>>> L = dict(x = 42, y = 3.14, z = 7)
>>> Double = [{
'x': 42,
'y': 3.14,
'z': 7
}, {
1: 2,
3: 4
}, {
'w': 14
}] >>>
Double[0] {
'y': 3.1400000000000001,
'x': 42,
'z': 7
}>>> FirstDict = Double[0] >>>
FirstDict['x']
42>>> Double[0]['x']
42When looping through dictionaries, the key and corresponding value can be retrieved at the same time using the items() method.,When looping through a sequence, the position index and corresponding value can be retrieved at the same time using the enumerate() function.,To loop over two or more sequences at the same time, the entries can be paired with the zip() function.,Note that this creates (or overwrites) a variable named x that still exists after the loop completes. We can calculate the list of squares without any side effects using:
>>> fruits = ['orange', 'apple', 'pear', 'banana', 'kiwi', 'apple', 'banana'] >>>
fruits.count('apple')
2
>>>
fruits.count('tangerine')
0
>>>
fruits.index('banana')
3
>>>
fruits.index('banana', 4) # Find next banana starting a position 4
6
>>>
fruits.reverse() >>>
fruits['banana', 'apple', 'kiwi', 'banana', 'pear', 'apple', 'orange'] >>>
fruits.append('grape') >>>
fruits['banana', 'apple', 'kiwi', 'banana', 'pear', 'apple', 'orange', 'grape'] >>>
fruits.sort() >>>
fruits['apple', 'apple', 'banana', 'banana', 'grape', 'kiwi', 'orange', 'pear'] >>>
fruits.pop()
'pear'>>> stack = [3, 4, 5] >>> stack.append(6) >>> stack.append(7) >>> stack[3, 4, 5, 6, 7] >>> stack.pop() 7 >>> stack[3, 4, 5, 6] >>> stack.pop() 6 >>> stack.pop() 5 >>> stack[3, 4]
>>> from collections
import deque
>>>
queue = deque(["Eric", "John", "Michael"]) >>>
queue.append("Terry") # Terry arrives >>>
queue.append("Graham") # Graham arrives >>>
queue.popleft() # The first to arrive now leaves 'Eric' >>>
queue.popleft() # The second to arrive now leaves 'John' >>>
queue # Remaining queue in order of arrival
deque(['Michael', 'Terry', 'Graham'])>>> squares = [] >>> for x in range(10): ...squares.append(x ** 2) ... >>> squares[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
squares = list(map(lambda x: x ** 2, range(10)))
squares = [x ** 2 for x in range(10) ]
Updates the dictionary with the specified key-value pairs. If the key exists, the value will be updated. If the key does not exist, the value will be inserted using the given key.
dictionary.update(dict[, ** pairs])
dictionary.update(iterable[, ** pairs])for key in dict: dictionary[key] = dict[key]
for key, value in iterable: dictionary[key] = value
fish = {
'guppy': 2,
'zebra': 5,
'betta': 10
}
fish.update({
'guppy': 3,
'shark': 1
})
print(fish)Output
{
'guppy': 3,
'zebra': 5,
'betta': 10,
'shark': 1
}for key in dict: dictionary[key] = dict[key]
for key, value in iterable: dictionary[key] = value
for key in pairs: dictionary[key] = pairs[key]
Insert value into the dictionary p with a key of key. key must be hashable; if it isn’t, TypeError will be raised. Return 0 on success or -1 on failure.,Remove the entry in dictionary p with key key. key must be hashable; if it isn’t, TypeError is raised. Return 0 on success or -1 on failure.,Insert value into the dictionary p using key as a key. key should be a char*. The key object is created using PyUnicode_FromString(key). Return 0 on success or -1 on failure.,Remove the entry in dictionary p which has a key specified by the string key. Return 0 on success or -1 on failure.
PyObject * key, * value;
Py_ssize_t pos = 0;
while (PyDict_Next(self - > dict, & pos, & key, & value)) {
/* do something interesting with the values... */
...
}PyObject * key, * value;
Py_ssize_t pos = 0;
while (PyDict_Next(self - > dict, & pos, & key, & value)) {
long i = PyLong_AsLong(value);
if (i == -1 && PyErr_Occurred()) {
return -1;
}
PyObject * o = PyLong_FromLong(i + 1);
if (o == NULL)
return -1;
if (PyDict_SetItem(self - > dict, key, o) < 0) {
Py_DECREF(o);
return -1;
}
Py_DECREF(o);
}def PyDict_MergeFromSeq2(a, seq2, override):
for key, value in seq2:
if override or key not in a:
a[key] = value