Server Side Programming Articles - Page 1919 of 2646

What is 2-3 Trees? A 2-3 tree is a tree data structure, where each internal node has either 2 or 3 children (also, we can say that 2-nodes and 3-nodes, respectively). It is a type of B-tree that ensures efficient search, insertion, and deletion operations with O(logn) time complexity. Properties of 2-3 tree 2-node contains one data element and has two children (or none if it is a leaf). 3-node contains two data elements and has three children (or none if it is a leaf). Data ... Read More

In the 0-1 knapsack problem, a set of items is given, each with a weight and a value. We need to determine the number of each item to include in a collection so that the total weight is less than or equal to the given limit and the total value is as large as possible. What is Branch and Bound Algorithm?The branch and bound algorithm breaks the given problem into multiple sub-problems and then uses a bounding function. It eliminates only those solutions that cannot provide optimal solutions. In this article, we will discuss how to solve the 0-1 knapsack problem ... Read More

You can format any time as per your requirement, but simple method to get time in readable format is asctime() −Example Live Demo#!/usr/bin/python import time; localtime = time.asctime( time.localtime(time.time()) ) print "Local current time :", localtimeOutputThis would produce the following result −Local current time : Tue Jan 13 10:17:09 2009

To translate a time instant from a seconds since the epoch floating-point value into a time-tuple, pass the floating-point value to a function (e.g., localtime) that returns a time-tuple with all nine items valid.Example Live Demo#!/usr/bin/python import time; localtime = time.localtime(time.time()) print "Local current time :", localtimeOutputThis would produce the following result, which could be formatted in any other presentable form −Local current time : time.struct_time(tm_year=2013, tm_mon=7, tm_mday=17, tm_hour=21, tm_min=26, tm_sec=3, tm_wday=2, tm_yday=198, tm_isdst=0)

Many of Python's time functions handle time as a tuple of 9 numbers, as shown below −IndexFieldValues04-digit year20081Month1 to 122Day1 to 313Hour0 to 234Minute0 to 595Second0 to 61 (60 or 61 are leap-seconds)6Day of Week0 to 6 (0 is Monday)7Day of year1 to 366 (Julian day)8Daylight savings-1, 0, 1, -1 means library determines DSTThe above tuple is equivalent to struct_time structure. This structure has following attributes −IndexAttributesValues0tm_year20081tm_mon1 to 122tm_mday1 to 313tm_hour0 to 234tm_min0 to 595tm_sec0 to 61 (60 or 61 are leap-seconds)6tm_wday0 to 6 (0 is Monday)7tm_yday1 to 366 (Julian day)8tm_isdst-1, 0, 1, -1 means library determines DSTRead More

Python includes the following dictionary functions −Sr.NoFunction with Description1cmp(dict1, dict2)Compares elements of both dict.2len(dict)Gives the total length of the dictionary. This would be equal to the number of items in the dictionary.3str(dict)Produces a printable string representation of a dictionary4type(variable)Returns the type of the passed variable. If passed variable is dictionary, then it would return a dictionary type.Python includes following dictionary methods −Sr.NoMethods with Description1dict.clear()Removes all elements of dictionary dict2dict.copy()Returns a shallow copy of dictionary dict3dict.fromkeys()Create a new dictionary with keys from seq and values set to value.4dict.get(key, default=None)For key key, returns value or default if key not in dictionary5dict.has_key(key)Returns true ... Read More

Dictionary values have no restrictions. They can be any arbitrary Python object, either standard objects or user-defined objects. However, same is not true for the keys.There are two important points to remember about dictionary keys −More than one entry per key not allowed. Which means no duplicate key is allowed. When duplicate keys encountered during assignment, the last assignment wins.ExampleFollowing is a simple example − Live Demo#!/usr/bin/python dict = {'Name': 'Zara', 'Age': 7, 'Name': 'Manni'} print "dict['Name']: ", dict['Name']OutputWhen the above code is executed, it produces the following result −dict['Name']: Manni Keys must be immutable. Which means you can use strings, ... Read More

You can either remove individual dictionary elements or clear the entire contents of a dictionary. You can also delete entire dictionary in a single operation.To explicitly remove an entire dictionary, just use the del statement.ExampleFollowing is a simple example − Live Demo#!/usr/bin/python dict = {'Name': 'Zara', 'Age': 7, 'Class': 'First'} del dict['Name']; # remove entry with key 'Name' dict.clear(); # remove all entries in dict del dict ; # delete entire dictionary print "dict['Age']: ", dict['Age'] print "dict['School']: ", dict['School']OutputThis produces the following result. Note that an exception is raised because after del dict dictionary does not exist any more −dict['Age']: Traceback (most ... Read More

You can update a dictionary by adding a new entry or a key-value pair, modifying an existing entry, or deleting an existing entry as shown below in the simple example −Example Live Demo#!/usr/bin/python dict = {'Name': 'Zara', 'Age': 7, 'Class': 'First'} dict['Age'] = 8; # update existing entry dict['School'] = "DPS School"; # Add new entry print "dict['Age']: ", dict['Age'] print "dict['School']: ", dict['School']OutputWhen the above code is executed, it produces the following result −dict['Age']: 8 dict['School']: DPS School

Accessing Values of Dictionary in Python Accessing dictionary items in Python involves retrieving the values associated with specific keys within a dictionary data structure. Dictionaries are composed of key-value pairs, where each key is unique and maps to a corresponding value. Accessing dictionary items allows us to retrieve these values by providing the respective keys. There are various ways to access dictionary items in Python. They include − Using square brackets[] The get() method Using keys() Method Using values() Method ... Read More