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Programming Articles
Page 2373 of 2547
Importance of the Collectors.filtering() method in Java 9?
Collectors class is an essential part of the Stream API. In Java 9, a new method: filtering() added to the Collectors class. The Collectors.filtering() method can be used for filtering elements in a stream. It is similar to the filter() method on streams. The filter() method processes the values before they have grouped whereas the filtering() method can be used nicely with the Collectors.groupingBy() method to group the values before the filtering step takes place.Syntaxpublic static Collector filtering(Predicate
Read MoreHow can I loop over entries in JSON using Python?
You can parse JSON files using the json module in Python. This module parses the json and puts it in a dict. You can then get the values from this like a normal dict. For example, if you have a json with the following content −{ "id": "file", "value": "File", "popup": { "menuitem": [ {"value": "New", "onclick": "CreateNewDoc()"}, {"value": "Open", "onclick": "OpenDoc()"}, {"value": "Close", "onclick": "CloseDoc()"} ...
Read MoreWhat is a forward reference in JShell in Java 9?
JShell is a command-line tool that allows us to enter Java statements (simple statements, compound statements, or even full methods and classes), evaluates it and prints the result.Forward references are commands that refer to methods, variables, or classes that don't exist in any code we have typed in JShell. As code entered and evaluated sequentially in JShell, these forward references have temporarily unresolved. JShell supports forward references in method bodies, return types, parameter types, variable types, and within a class.In the below code snippet, created a method forwardReference() in Jshell. This method can't be invoked until the variable is declared. ...
Read MoreHow can we do Python operator overloading with multiple operands?
You can do Python operator overloading with multiple operands just like you would do it for binary operators. For example, if you want to overload the + operator for a class, you'd do the following −Exampleclass Complex(object): def __init__(self, real, imag): self.real = real self.imag = imag def __add__(self, other): real = self.real + other.real imag = self.imag + other.imag return Complex(real, imag) def display(self): print(str(self.real) + " + " + str(self.imag) + "i") a = Complex(10, 5) b = Complex(5, 10) c = Complex(2, 2) d = a + b + c d.display()OutputThis will give the output −17 + 17i
Read MoreHow to view a list of all Python operators via the interpreter?
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')
Read MoreWhat do the =+ and += do in Python?
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 MoreHow to find the average of non-zero values in a Python dictionary?
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.
Read MoreFinding The Biggest Key In A Python Dictionary?
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.
Read MoreDo you think Python Dictionary is really Mutable?
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}
Read MoreHow can I convert Python dictionary to JavaScript hash table?
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 ...
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