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The help method in the interpreter is very useful for such operations. It provides a rich set of special inputs that you can give to it to get information about the different aspects of the language. Forgetting operator lists, here are some of the commands you can use:All operators>>> help('SPECIALMETHODS')Basic operators>>> help('BASICMETHODS')Numeric operators>>> help('NUMBERMETHODS')Other than operators you can also get attribute methods, callable methods, etc using −>>> help('MAPPINGMETHODS') >>> help('ATTRIBUTEMETHODS') >>> help('SEQUENCEMETHODS1') >>> help('SEQUENCEMETHODS2') >>> help('CALLABLEMETHODS')
The += operator is syntactic sugar for object.__iand__() function. From the python docs:These methods are called to implement the augmented arithmetic assignments (+=, -=, *=, @=, /=, //=, %=, **=, =, &=, ^=, |=). These methods should attempt to do the operation in-place (modifying self) and return the result (which could be, but does not have to be, self).ExampleSo when you do something like −a = 6 # 110 in binary b = 5 # 101 in binary a &= b # a changes to and of 110 and 101, ie, 100, ie, 4 print(a)OutputThis will give the output −15a ... Read More
Suppose we have the root of a binary tree, each node in the tree has a unique value. After removing all nodes with a value in to_delete, we are left with a forest. We have to find the roots of the trees in the remaining forest. So if the input is likeif the to_delete array is like [3, 5], then the output will beTo solve this, we will follow these steps −Define an array resDefine a method solve(), this will take node, to_delete array and a Boolean type info to which is telling that the node is root or not. ... Read More
The += operator is syntactic sugar for object.__iadd__() function. From the python docs:These methods are called to implement the augmented arithmetic assignments (+=, -=, *=, @=, /=, //=, %=, **=, =, &=, ^=, |=). These methods should attempt to do the operation in-place (modifying self) and return the result (which could be, but does not have to be, self).ExampleSo when you do something like −a = 5 b = 10 a += b print(a)OutputThis will give the output −15a is being modified in place here. You can read more about such operators on https://docs.python.org/3/reference/datamodel.html#object.__iadd__.The =+ operator is the same as ... Read More
You can do this by iterating over the dictionary and filtering out zero values first. Then take the sum of the filtered values. Finally, divide by the number of these filtered values. examplemy_dict = {"foo": 100, "bar": 0, "baz": 200} filtered_vals = [v for _, v in my_dict.items() if v != 0] average = sum(filtered_vals) / len(filtered_vals) print(average)OutputThis will give the output −150.0You can also use reduce but for a simple task such as this, it is an overkill. And it is also much less readable than using a list comprehension.
The easiest and most readable way to access nested properties in a Python dict is to use for loop and loop over each item while getting the next value, until the end. exampledef getFromDict(dataDict, mapList): for k in mapList: dataDict = dataDict[k] return dataDict a = { 'foo': 45,'bar': { 'baz': 100,'tru': "Hello" } } print(getFromDict(a, ["bar", "baz"]))OutputThis will give the output −100
If you have a dict with string-integer mappings, you can use the max method on the dictionary's item pairs to get the largest value. exampled = { 'foo': 100, 'bar': 25, 'baz': 360 } print(max(k for k, v in d.items()))OutputThis will give the output −foofoo is largest in alphabetical order.
Suppose we have a sequence of books − Here the i-th book has thickness books[i][0] and height books[i][1]. If we want to place these books in order onto bookshelves that have total width shelf_width. If we choose some of the books to place on this shelf (such that the sum of their thickness is = 0 and temp – books[j, 0] >= 0, docurr_height := max of books[j, 1], curr_heightdp[i] := min of dp[i], curr_height + (dp[j - 1] if j – 1 >= 0, otherwise 0)temp := temp – books[j, 0]decrease j by 1return last element of dpLet us ... Read More
Yes, Python Dictionary is mutable. Changing references to keys doesn't lead to the creation of new dictionaries. Rather it updates the current dictionary in place. examplea = {'foo': 1, 'bar': 12} b = a b['foo'] = 20 print(a) print(b)OutputThis will give the output −{'foo': 20, 'bar': 12} {'foo': 20, 'bar': 12}
Python and javascript both have different representations for a dictionary. So you need an intermediate representation in order to pass data between them. The most commonly used intermediate representation is JSON, which is a simple lightweight data-interchange format.The dumps function converts the dict to a string. exampleimport json my_dict = { 'foo': 42, 'bar': { 'baz': "Hello", 'poo': 124.2 } } my_json = json.dumps(my_dict) print(my_json)OutputThis will give the output −'{"foo": 42, "bar": {"baz": "Hello", "poo": 124.2}}'exampleThe load's function converts the string back to a dict. import json my_str = '{"foo": 42, "bar": {"baz": "Hello", "poo": 124.2}}' my_dict ... Read More