Python Articles

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Support for line-oriented command interpreters in Pytho

Ankith Reddy
Ankith Reddy
Updated on 26-Jun-2020 514 Views

The cmd module contains only one class called Cmd. This is used as base class for a user defined framework for line oriented command line interpreters.CmdAn object of this class or its subclass provides the line oriented interpreter framework. Important methods of this class inherited by the subclass are listed below.cmdloop()This method sends the object in a loop, accepts inputs and sends the same to appropriate command handler method in the class.As the loop starts an introductory message (give as parameter to cmdloop() method) will be displayed with a default (cmd) prompt which may be customized by prompt attribute.The interpreter ...

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How to pass Drop Down Box Data to Python CGI script?

Rajendra Dharmkar
Rajendra Dharmkar
Updated on 25-Jun-2020 611 Views

Passing Drop Down Box Data to CGI ProgramDrop Down Box is used when we have many options available but only one or two will be selected.Here is example HTML code for a form with one drop down box − Maths Physics The result of this code is the following form − SubmitBelow is dropdown.py script to handle input given by web browser.#!/usr/bin/python # Import modules for CGI handling import cgi, cgitb # Create instance of FieldStorage form ...

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High-level file operations in Python (shutil)

Chandu yadav
Chandu yadav
Updated on 25-Jun-2020 1K+ Views

A number of functions for hgh level operations on files and directories have been defined in shutil module of Python’s standard library.copy()This function copies a file to a specified file in same or other directory. First parameter to the function is a string representation of existing file. Second argument is either name of resultant file or directory. If it is a directory, the file is coped in it with same name. The metadata of original file is not maintained.>>> import shutil >>> shutil.copy("hello.py", "newdir/") 'newdir/hello.py'copy2()This function is similar to copy() function except for the fact that it retains metadata of ...

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The most Common POSIX System Calls in Python

Arjun Thakur
Arjun Thakur
Updated on 25-Jun-2020 1K+ Views

The posix module is works on the UNIX environment. It provides the Operating system functionality.We should not import this module directly. We can use the os module. The os module is acts as a superset of the posix module on UNIX. On non-Unix system the posix is not available, but the os is available with some less functionality.To use the posix module, we should import it using.import posixThere are different methods and constants in the POSIX module.Constant posix.environThe environ is a dictionary object. It holds keys and values. The keys and values are of bytes type for UNIX. For example, ...

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Python Context Manager Types

Chandu yadav
Chandu yadav
Updated on 25-Jun-2020 260 Views

In python, the runtime context is supported by the with statement. The context is defined by the context manager. Using the context manager, we can create user defined classes to define the runtime context. It enters into the task before executing the statement body, and when the statement body is completed, it ends.There are two different methods for context manager. These methods are −Method __enter__()The __enter__() method is used to enter into the runtime context. It will return either the current object or another related object. The returned value is bound to the identifier in as clause of the with ...

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Iterate over lines from multiple input streams in Python

Ankith Reddy
Ankith Reddy
Updated on 25-Jun-2020 777 Views

Python’s built-in open() function opens one file in read/write mode and read/write operations on it. To perform processing on multiple files in a batch, one has to use fileinput module of Python’s standard library. This module provides a Fileinput class with functionality of iterating over files. The module also defines helper functions for the same purpose.Primary interface to this module is input() function. This function returns instance of Fileinput class.fileinput.input(files, inplace, mode)The files parameter is name of one or more files to be read one by one. Each file acts as a generator and using a for loop it can ...

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Random access to text lines in Python (linecache)

Chandu yadav
Chandu yadav
Updated on 25-Jun-2020 1K+ Views

Purpose of linecache module in Python’s standard library is to facilitate random access to any text file, although this module is extensively used by Python’s traceback module to generate error trace stack. Further prettyprints of reading are held in a cache so that it saves time while reading lines repeatedly.The most important function in this module is getline() which reads a specified line number from given file. Following is the list of functions −getline(file, x)This function returns xth line from file. If not present it will return empty string. If the file is not present in current path, function ties ...

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File and Directory Comparisons in Python

George John
George John
Updated on 25-Jun-2020 6K+ Views

Python’s standard library has filecmp module that defines functions for comparison of files and directories. This comparison takes into consideration the properties of files in addition to data in them.Example codes in this article use following file and directory structure.Two directories dir1 and dir2 are first created under current working directory. They contain following files.--dir1/newfile.txt-- This is a file in dir1 --dir1/file1.txt-- Hello Python --dir1/file2.txt-- Python Standard Library --dir2/file1.txt-- Hello Python --dir2/file2.txt-- Python LibraryLet us now describe various comparison functions in filecmp module.filecmp.cmp(f1, f2, shallow=True)This function compares the two files and returns True if they are identical, False otherwise. The ...

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Prefix sum array in python using accumulate function

karthikeya Boyini
karthikeya Boyini
Updated on 25-Jun-2020 590 Views

Given an array and we have to do the prefix sum array using accumulate function.itertools.accumulate(iterable[, func]) module functions all construct and return iterators. So they should only be accessed by functions or loops that truncate the stream. Make an iterator that returns accumulated sums. Elements may be any addable type including Decimal or Fraction. If the optional function argument is supplied, it should be a function of two arguments and it will be used instead of addition.ExampleInput Data = [1, 0, 2, 3, 5] >>> list(accumulate(data)) # running summation Output [1, 1, 3, 6, 11]AlgorithmStep 1: Create list. Step 2: ...

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Can someone help me fix this Python Program?

Arnab Chakraborty
Arnab Chakraborty
Updated on 24-Jun-2020 157 Views

The first problem u are getting in the bold portion is due to non-indent block, put one indentation there.second problem is name variable is not definedfollowing is the corrected one -print ("Come-on in. Need help with any bags?") bag=input ('(1) Yes please  (2) Nah, thanks   (3) Ill get em later  TYPE THE NUMBER ONLY') if bag == ('1'): print ("Ok, ill be right there!") if bag == ('2'): print ("Okee, see ya inside. Heh, how rude of me? I'm Daniel by the way, ya?") name="Daniel" print (name + ": Um, Names " + name) print ("Dan: K, nice too ...

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