Python remove redundant parentheses

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Taking inputs (stdin)

OneCompiler’s python online editor supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample python program which takes name as input and print your name with hello.

import sys name = sys.stdin.readline() print("Hello "+ name)

About Python

Python is a very popular general-purpose programming language which was created by Guido van Rossum, and released in 1991. It is very popular for web development and you can build almost anything like mobile apps, web apps, tools, data analytics, machine learning etc. It is designed to be simple and easy like english language. It’s is highly productive and efficient making it a very popular language.

Tutorial & Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition IF-ELSE is used.

if conditional-expression #code elif conditional-expression #code else: #code

Note:

Indentation is very important in Python, make sure the indentation is followed correctly

2. For:

For loop is used to iterate over arrays(list, tuple, set, dictionary) or strings.

Example:

mylist=("Iphone","Pixel","Samsung") for i in mylist: print(i)

3. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

Collections

There are four types of collections in Python.

1. List:

List is a collection which is ordered and can be changed. Lists are specified in square brackets.

Example:

mylist=["iPhone","Pixel","Samsung"] print(mylist)

2. Tuple:

Tuple is a collection which is ordered and can not be changed. Tuples are specified in round brackets.

Example:

myTuple=("iPhone","Pixel","Samsung") print(myTuple)

Below throws an error if you assign another value to tuple again.

myTuple=("iPhone","Pixel","Samsung") print(myTuple) myTuple[1]="onePlus" print(myTuple)

3. Set:

Set is a collection which is unordered and unindexed. Sets are specified in curly brackets.

Example:

4. Dictionary:

Dictionary is a collection of key value pairs which is unordered, can be changed, and indexed. They are written in curly brackets with key — value pairs.

Example:

Supported Libraries

Following are the libraries supported by OneCompiler’s Python compiler

Name	Description
NumPy	NumPy python library helps users to work on arrays with ease
SciPy	SciPy is a scientific computation library which depends on NumPy for convenient and fast N-dimensional array manipulation
SKLearn/Scikit-learn	Scikit-learn or Scikit-learn is the most useful library for machine learning in Python
Pandas	Pandas is the most efficient Python library for data manipulation and analysis
Matplotlib	Matplotlib is a cross-platform, data visualization and graphical plotting library for Python programming and it’s numerical mathematics extension NumPy
DOcplex	DOcplex is IBM Decision Optimization CPLEX Modeling for Python, is a library composed of Mathematical Programming Modeling and Constraint Programming Modeling

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Settings when you want to code in accordance with PEP8

PyCharm from the menu column on the top left File -> Settings -> Editor -> Inspections -> Python -> PEP8 coding style violation to increase week warning to warning. It also changes the setting of PEP8 naming convention violation under it to warning.

Error Statement and How to Fix It

The following is how to deal with specific errors. These errors are called static analysis, and PyCharm checks for them immediately even in the free version. This results in better bug prevention and readability.

PEP8 do not use bare except

And when the warning comes out except: ↓ except FileNotFoundError: And so on, describe the error pattern. Once you give an error and check it, you will know what the error is.

Function name should be lowercase

Remove redundant parentheses

Just remove the extra parentheses class ClassA(): ↓ class ClassA:

PEP8: expected 2 blank lines, found 1

Just change the whitespace in one line to two lines

PEP8: expected 2 black lines after class or function definition, found 1

Just change the whitespace in one line to two lines

PEP8: block comment should start with ‘# ‘

PEP8: identation contains mixed spaces and tabs

Indentation mixes spaces and tabs

Method «xxx» may be ‘static’

Precede a line of method with a @staticmethod

Shadows built-in name ‘xx’

Overlaps with the existing (built-in) name ‘xx’ (shadow obscurity). Try to eliminate it because it will become a hotbed of bugs

continuation line under-indented for visual indent

(Continuation lines are not indented for visual indentation) Enumerate the arguments from the second line without leaving them on the first line. A bit complicated

simplify chained comparison

(Simplify chained comparisons) In the case of PyCharm, press Alt + Shift + Enter to automatically correct

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Remove Redundant Parenthesis in an Arithmetic Expression

Remove Redundant Parenthesis in an Arithmetic Expression

I’m trying to remove redundant parentheses from an arithmetic expression. For example, if I have the expression (5+((2*3))) , I want the redundant parenthesis between (2*3) removed. The output that I want is (5+(2*3)) .

I’m getting this arithmetic expression from performing an inorder traversal on an expression tree. The final string that I get after performing the traversal is ((5)+(((2)*(3)))) . I used re.sub(‘((d+))’, r’1′, ) to remove the parenthesis between the numbers like (5) to 5 . But I’m still confused on how I should approach to remove parenthesis among sub expressions ( ((2*3)) in this case).

Here is what my inorder traversal function looks like

 def inorder(tree): # return string of inorder traversal of tree with parenthesis s = '' if tree != None: s += '(' s += ExpTree.inorder(tree.getLeftChild()) s += str(tree.getRootVal()) s += ExpTree.inorder(tree.getRightChild()) s += ')' return re.sub('((d+))', r'1', s) 

Any guidance on how I should approach to solve this problem would be appreciated!

Solution – 1

Instead of adding the parenthesis around the parent/root expression, one option is to add the parentheses before and after recursing down on each of the left and right children. If those children are leaves, meaning they do not have children, do not add parentheses.

In practice, this might look something like this:

def inorder(tree): # return string of inorder traversal of tree with parenthesis s = '' # Add left subtree, with parentheses if it is not a leaf left = tree.getLeftChild() if left is not None: if left.isLeaf(): s += ExpTree.inorder(left) else: s += '(' + ExpTree.inorder(left) + ')' # Add root value s += str(tree.getRootVal()) # Add right subtree, with parentheses if it is not a leaf right = tree.getRightChild() if right is not None: if right.isLeaf(): s += ExpTree.inorder(right) else: s += '(' + ExpTree.inorder(right) + ')' return s 

This means that a tree with a single node, 5, will become just «5» , and the following tree

To instead get the output «(5+((2*3)))» , add an additional set of parenthesis around the returned string if the tree is not a leaf.

def inorder(tree): # return string of inorder traversal of tree with parenthesis s = '' # Add left subtree, with parentheses if it is not a leaf left = tree.getLeftChild() if left is not None: if left.isLeaf(): s += ExpTree.inorder(left) else: s += '(' + ExpTree.inorder(left) + ')' # Add root value s += str(tree.getRootVal()) # Add right subtree, with parentheses if it is not a leaf right = tree.getRightChild() if right is not None: if right.isLeaf(): s += ExpTree.inorder(right) else: s += '(' + ExpTree.inorder(right) + ')' # Add an additional set of parenthesis around non-leaf expressions. if tree.isLeaf(): return s else: return '(' + s + ')' 

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Русские Блоги

Python3 отмечает исследование характеристики 36-PEP8 код

При использовании PyCharm, ультраправое будет иметь волнистую линию код предупреждения не соответствуетСтандарты PEP8 кодОтказ Запишите то, что было неправильно и совершенные решения

PEP8 стиль неправильно, а не ошибок кодирования. Просто, чтобы сделать код более читаемость.

1）block comment should start with #

Этот совет при использовании # комментария, вам необходимо добавить пробел после #, а затем написать комментарий содержание

2) отсутствует пробел после «» или отсутствующий пробел после „:“

При использовании, или: когда нужно пространство для раскола в спине

Совет, не нужно пространство впереди, удалить пустое пространство

4）class name should use CamelCase convention

Название Совет класс должен использовать слово заглавной путь к имени, введите первую букву каждого слова в названии

5）expected 2 blank lines ，found 1

Это побудило две пустые строки. Найдено только 0 или 1. Может наноситься на две пустые строки

6）remove redundant parentheses

Запрашивает снять скобки, если класс не наследует другие классы. Может не нужно добавлять после имени класса (). () Могут быть удалены

7）Triple double-quoted strings should be used for docstrings

Вы должны использовать три двойные кавычки. Написать в классе и метод с использованием комментариев одиночных кавычек. Заменено двойные кавычки на нем

Подсказка пустая строка между слишком много и метод пустой линии на линии

9）shadows name ‘xxxx’ from outer scope

Naming конфликтов, предполагая, что внешние переменные и локальные переменные в методе именования то же самое. Совет риск. Под именем переменной может быть изменено

10）Too broad exception clause

Совет поймать исключение слишком широким, и не направлены. Вы можете добавлять комментарии в Ьгу заявление

# noinspection PyBroadException

11）argument name should be lowercase

Имя параметра должно быть в нижнем регистре

12）missing whitespace around operator

Отсутствие пробелов по обе стороны знака равенства

13）blank line at end of file

В конце коды, есть еще пустые строки, только пустая строка

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