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To extract CSV file for specific columns to list in python, we can use Pandas read_csv() method.StepsMake a list of columns that have to be extracted.Use read_csv() method to extract the CSV file data into a data frame.Print the exracted data.Plot the data frame using plot() method.To display the figure, use show() method.Exampleimport pandas as pd from matplotlib import pyplot as plt plt.rcParams["figure.figsize"] = [7.00, 3.50] plt.rcParams["figure.autolayout"] = True columns = ["Name", "Marks"] df = pd.read_csv("input.csv", usecols=columns) print("Contents in csv file:", df) plt.plot(df.Name, df.Marks) plt.show()OutputRead More
The following code shows how to get return value from a function in a Python class.Exampleclass Score(): def __init__(self): self.score = 0 self.num_enemies = 5 self.num_lives = 3 def setScore(self, num): self.score = num def getScore(self): return self.score def getEnemies(self): return self.num_enemies def getLives(self): return self.num_lives s = Score() s.setScore(9) print s.getScore() print s.getEnemies() print s.getLives()Output9 5 3
To upload a file, the HTML form must have the enctype attribute set to multipart/form-data. The input tag with the file type creates a "Browse" button.Example File: OutputThe result of this code is the following form −File: Choose file UploadHere is the script save_file.py to handle file upload −#!/usr/bin/python import cgi, os import cgitb; cgitb.enable() form = cgi.FieldStorage() # Get filename here. fileitem = form['filename'] # Test if the file was uploaded if fileitem.filename: # strip leading path from file name to avoid # directory traversal attacks ... Read More
Suppose there is an HTML file as below − FirstName: LastName: After submitting this form it should go to a Python page named "getData.py", where you should fetch the data from this HTML page and show. then below is the code for Python CGI. #!C:\Python27\python.exe # Import modules for CGI handling import cgi, cgitb # Create instance of FieldStorage form = cgi.FieldStorage() # Get data from fields first_name = form.getvalue('first_name') last_name = form.getvalue('last_name') print("Content-type:text/html") print print("") print("") print("Hello - Second CGI Program") print("") print("") print(" ... Read More
While creating a function the single asterisk (*) defined to accept and allow users to pass any number of positional arguments. And in the same way the double asterisk (**) defined to accept any number of keyword arguments. The single asterisk (*) can be used when we are not sure how many arguments are going to be passed to a function and those arguments that are not keywords. The double asterisk (**kwargs) can be used to pass keywords, when we don't know how many keyword arguments will be passed to a function, which will be in a dict named ... Read More
The double star/asterisk (*) operator has more than one meaning in Python. We can use it as a exponential operator, used as function *kwargs, unpacking the iterables, and used to Merge the Dictionaries. Exponential operator For numeric data the double asterisk (**) is used as an exponential operator. Let's take an example and see how the double star operator works on numeric operands. Example The following example uses double asterisks/star (**) to calculate “a to the power b” and it works equivalent to the pow() function. a = 10 b = 2 result = a ** b print("a**b = ", ... Read More
In Python, 'not in' membership operator evaluates to true if it does not finds a variable in the specified sequence and false otherwise. For example >>> a = 10 >>> b = 4 >>> l1 = [1,2,3,4,5] >>> a not in l1 True >>> b not in l1 False Since 'a' doesn't belong to l1, a not in b returns True. However, b can be found in l1, hence b not in l1 returns False
In some languages like C / C++ the "!" symbol is used as a logical NOT operator. !x it returns true if x is false else returns false. The equivalent of this "!" operator in python is logical NOT, It also returns true if the operand is false and vice versa. Example In the Following example the variable operand_X holds a boolean value True, after applying the not operator it returns False. operand_X = True print("Input: ", operand_X) result = not(operand_X) print('Result: ', result) Output Input: True Result: False Example For False value the ... Read More
Python defines variety of data types of objects. These objects are stored in memory and object mutability depends upon the type, like Lists and Dictionaries are mutable it means that we can change their content without changing their identity. Other objects like Integers, Floats, Strings, and Tuples have no provision to change there assigned value for an index.List is mutable: Lists are just like the arrays, declared in other languages. Lists need not be homogeneous always which makes it a most powerful tool in Python. Lists are mutable, and hence, they can be altered even after their creation.Example#Write a python ... Read More
In this article, we will explain the immutable datatypes in Python. Python considers everything to be an object. A unique id is assigned to it when we instantiate an object. We cannot modify the type of object, but we may change its value. For example, if we set variable a to be a list, we can't change it to a tuple/dictionary, but we may modify the entries in that list. In Python, there are two kinds of objects. On the one hand, there are objects that can change their internal state (the data/content inside the objects), i.e. they can be ... Read More