Suppose we have a matrix of unique elements and a sum; we have to find all the pairs from the matrix whose sum is equal to given sum. Here, each element of pair will be taken from different rows.So, if the input is like −24356987101114121311516sum = 13, then the output will be [(2, 11), (4, 9), (3, 10), (5, 8), (12, 1)]To solve this, we will follow these steps −res := a new listn := size of matrixfor i in range 0 to n, dosort the list matrix[i]for i in range 0 to n - 1, dofor j in range ... Read More

File handling is an important part of any web application.Python has several functions for creating, reading, updating, and deleting files.To write to an existing file, you must add a parameter to the open()function −"a" − Append − will append to the end of the file"w" − Write − will overwrite any existing contentExampleimport os # list the files in directory lis = os.listdir('D:\python' '\data_files\data_files') print(lis) tgt = os.listdir('D:\python' '\data_files\target_file')   file_dir ='D:\python\data_files\data_files' out_file = r'D:\python\data_files\target_file\master.txt' ct = 0   print('target file :', tgt) try:    # check for if file exists    # if yes delete the file    # otherwise ... Read More

Matplotlib is an amazing visualization library in Python for 2D plots of arrays. Matplotlib is a multi-platform data visualization library built on NumPy arrays and designed to work with the broader SciPy stack.Example#applying pseudocolor # importing pyplot and image from matplotlib import matplotlib.pyplot as plt import matplotlib.image as img   # reading png image im = img.imread('imR.png')   # applying pseudocolor # default value of colormap is used. lum = im[:, :, 0]   # show image plt.imshow(lum) #colorbar # importing pyplot and image from matplotlib import matplotlib.pyplot as plt import matplotlib.image as img # reading png image im = ... Read More

Python Pandas is a data analysis library. It can read, filter and re-arrange small and large datasets and output them in a range of formats including Excel.Pandas writes Excel files using the XlsxWriter modules.XlsxWriter is a Python module for writing files in the XLSX file format. It can be used to write text, numbers, and formulas to multiple worksheets. Also, it supports features such as formatting, images, charts, page setup, auto filters, conditional formatting and many others.Example# import pandas as pd import pandas as pd # Create some Pandas dataframes from some data. df1 = pd.DataFrame({'Data': [11, 12, 13, 14]}) df2 = pd.DataFrame({'Data': [21, ... Read More

Word documents contain formatted text wrapped within three object levels. Lowest level- Run objects, Middle level- Paragraph objects and Highest level- Document object.So, we cannot work with these documents using normal text editors. But we can manipulate these word documents in python using the python-docx module.The first step is to install this third-party module python-docx. You can use pip “pip install python-docx”After installation import “docx” NOT “python-docx”.Use “docx.Document” class to start working with the word document.Example# import docx NOT python-docx import docx # create an instance of a word document doc = docx.Document() # add a heading of level 0 ... Read More

Word Embedding is a language modeling technique used for mapping words to vectors of real numbers. It represents words or phrases in vector space with several dimensions. Word embeddings can be generated using various methods like neural networks, co-occurrence matrix, probabilistic models, etc.Word2Vec consists of models for generating word embedding. These models are shallow two-layer neural networks having one input layer, one hidden layer and one output layer.Example# importing all necessary modules from nltk.tokenize import sent_tokenize, word_tokenize import warnings warnings.filterwarnings(action = 'ignore') import gensim from gensim.models import Word2Vec   #  Reads ‘alice.txt’ file sample = open("C:\Users\Vishesh\Desktop\alice.txt", "r") s = sample.read()   # ... Read More

Kivy is a platform independent GUI tool in Python. As it can be run on Android, IOS, linux and Windows etc. Kivy provides you the functionality to write the code for once and run it on different platforms. It is basically used to develop the Android application, but it does not mean that it can not be used on Desktops applications.Kivy is that platform where the size does not matter a lot as it is self-adjusting accordingly but What if we want to fix the size to some extent whether its hight wise or width wise or free from boundation depends ... Read More

Python is a very flexible language where a single task can be performed in a number of ways, for example initializing lists can be performed in many ways. However, there are subtle differences in these seemingly similar methods. Python which is popular for its simplicity and readability is equally infamous for being slow compared to C++ or Java. The ‘for’ loop is especially known to be slow whereas methods like map() and filter() known to be faster because they are written in C.Example Live Demo# import time module to calculate times import time # initialise lists to save the times forLoopTime ... Read More

While developing an application, there come many scenarios when we need to operate on the string and convert it as some mutable data structure, say list.Example# Importing ast library import ast # Initialization of strings str1 ="'Python', 'for', 'fun'" str2 ="'vishesh', 'ved'" str3 ="'Programmer'" # Initialization of list list = [] # Extending into single list for x in (str1, str2, str3):    list.extend(ast.literal_eval(x)) # printing output print(list) # using eval # Initialization of strings str1 ="['python, 'for', ''fun']" str2 ="['vishesh', 'ved']" str3 ="['programmer']" out = [str1, str2, str3] out = eval('+'.join(out)) # printing output print(out)

List is an important container and used almost in every code of day-day programming as well as web-development, more it is used, more is the requirement to master it and hence knowledge of its operations is necessary.Example# using itertools.ziplongest # import library from itertools import zip_longest   # initialising listoflist test_list = [    [('11'), ('12'), ('13')],    [('21'), ('22'), ('23')],    [('31'), ('32'), ('33')]    ] # printing intial list print ("Initial List = ", test_list)   # iterate list tuples list of list into single list res_list = [item for my_list in zip_longest(*test_list) for item in my_list if ... Read More