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Python Articles
Page 792 of 855
How to Parse HTML pages to fetch HTML tables with Python?
ProblemYou need to extract the HTML tables from a web page.IntroductionThe internet, and the World Wide Web (WWW), is the most prominent source of information today. There is so much information out there, it is just very hard to choose the content from so many options. Most of that information is retrievable through HTTP.But we can also perform these operations programmatically to retrieve and process information automatically.Python allows us to do this using its standard library an HTTP client, but the requests module helps in obtaining web pages information very easy.In this post, we will see how to parse through ...
Read MoreSelenium and Python to find elements and text?
We can find elements and its text with Selenium webdriver. First of all we have to identify the element with the help of any of the locators like id, classname, css and so on. Then to obtain the text we have to take the help of the text method.Syntaxs = driver.find_element_by_css_selector("h4").textHere driver is the webdriver object. The method find_element_by_css_selector is used to identify the element with css locator type and the locator value is passed as an argument to the method. Finally the text method is used to obtain the text content of the element.Let us look at the html of ...
Read MoreHow to set Selenium Python WebDriver default timeout?
We can set default timeout with Selenium webdriver. The method set_page_load_timeout is used to have a timeout for the page loading. The wait time in seconds is passed as parameter to the method.Syntaxdriver.set_page_load_timeout(5)A TimeoutException is thrown if the page is still not loaded after the wait time is passed.We can use the implicit wait concept in synchronization to define the default timeout time. This is a global wait time and applied to every element in the page. The method implicitly_wait is used to define implicit wait. The wait time in seconds is passed as parameter to the method.Syntaxdriver.implicitly_wait(5);A TimeoutException is ...
Read MoreWait until page is loaded with Selenium WebDriver for Python.
We can wait until the page is loaded with Selenium webdriver. There is a synchronization concept in Selenium which describes implicit and explicit wait. To wait until the page is loaded we shall use the explicit wait concept.The explicit wait is designed such that it is dependent on the expected condition for a particular behavior of an element. For waiting until the page is loaded we shall use the expected condition presence_of_element_loaded for a particular element. Once the wait time is elapsed, the timeout error shall be thrown.To implement explicit wait conditions, we have to take help of the WebDriverWait ...
Read MoreProgram to reverse linked list by groups of size k in Python
Suppose we have a singly linked list, and another value k, we have to reverse every k contiguous group of nodes.So, if the input is like List = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], k = 3, then the output will be [3, 2, 1, 6, 5, 4, 9, 8, 7, 10, ]To solve this, we will follow these steps −tmp := a new node with value 0next of tmp := nodeprev := null, curr := nulllp := temp, lc := currcnt := kwhile curr is not null, doprev := nullwhile cnt > 0 and curr ...
Read MoreProgram to reverse a linked list in Python
Suppose we have a linked list, we have to reverse it. So if the list is like 2 -> 4 -> 6 -> 8, then the new reversed list will be 8 -> 6 -> 4 -> 2.To solve this, we will follow this approach −Define one procedure to perform list reversal in recursive way as solve(head, back)if head is not present, then return headtemp := head.nexthead.next := backback := headif temp is empty, then return headhead := tempreturn solve(head, back)Let us see the following implementation to get better understanding −Exampleclass ListNode: def __init__(self, data, next = None): ...
Read MoreProgram to remove duplicate entries in a linked list in Python
Suppose we have a linked list of numbers, we have to remove those numbers which appear multiple times in the linked list (hold only one occurrence in the output), we also have to maintain the order of the appearance in the original linked list.So, if the input is like [2 -> 4 -> 6 -> 1 -> 4 -> 6 -> 9], then the output will be [2 -> 4 -> 6 -> 1 -> 9].To solve this, we will follow these steps −if node is not null, thenl := a new settemp := nodeinsert value of temp into lwhile ...
Read MoreProgram to find length of longest increasing subsequence in Python
Suppose we have a list of numbers. We have to find the length of longest increasing subsequence. So if the input is like [6, 1, 7, 2, 8, 3, 4, 5], then the output will be 5, as the longest increasing subsequence is [2, 3, 4, 5, 6].To solve this, we will follow these steps −Make an array called tails whose size is same as nums, and fill this with 0.size := 0for each element x in nums array −i := 0, j := sizewhile i is not same as j, thenmid := i + (j – i)/2if tails[mid] < ...
Read MoreProgram to create linked list to binary search tree in Python
Suppose we have a sorted linked list node of size n, we have to create a binary search tree by Taking the value of the k = floor of (n / 2) the smallest setting it as the root. Then recursively constructing the left subtree using the linked list left of the kth node. And recursively constructing the right subtree using the linked list right of the kth node.So, if the input is like [2, 4, 5, 7, 10, 15], then the output will beTo solve this, we will follow these steps−Define a method solve(), this will take nodeif node ...
Read MoreProgram to convert level order binary tree traversal to linked list in Python
Suppose we have a binary search tree, we have to convert it to a singly linked list using levelorder traversal.So, if the input is likethen the output will be [5, 4, 10, 2, 7, 15, ]To solve this, we will follow these steps −head := a new linked list nodecurrNode := headq := a list with value rootwhile q is not empty, docurr := delete first element from qif curr is not null, thennext of currNode := a new linked list node with value of currcurrNode := next of currNodeinsert left of curr at the end of qinsert right curr ...
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