Applied Data Science with Python Specialization

#datetime and calendar module:

A date is not a datatype of its own, but we can import module named datetime to work with dates as date object. This module has many methods to return information about the date object. Methods such as strftime(). Calendar module is an in-built module which handles operations related to calendar. It has methods such as itermonthdates(), yeardatescalendar() etc.

#exception handling:

Exception is a condition in a program code. It is basically an error which happens during the execution of the program. It must be either handled immediately otherwise it terminates or quits. This can be handle by placing code in try block. After try include except.

# create, edit, write, read text:

Files are persistent because the run for a long time, they keep some data in permanent storage. Opening a file for writing uses the built-in function that is open(). This returns a file object. Write function takes one parameter, which is the string to be written. Read function for getting the characters read in the file. Edit will simply make some editing in your file.

#Collection Module-

Collection are basically type of containers that are used to store collections of data for example list, dict, tuples etc. These are built-in collections. It was introduced to improve the functionalities of the built-in collection containers. There are so many functions in this module like counter which takes an iterable. The other is element() which gets the items of a counter object. And many such funtions.

#RegularExpression-

The regular expression can be defined as a specific type of text pattern. These patterns you can use with many applications and programming languages. By using this you can verify whether the inputs fit into the text pattern, to replace text matching the pattern, to find text. The re module raises re.error if error occurs and many such things.

#list comprehension, fronzen set function-

It is a way to define or create a list. These lists have often qualities of sets, but are not in all cases sets. It is a complete substitute of lambda function and map, filter and reduce function. The frozen set is an inbuilt function. It takes an iterable object as input and makes them immutable that is unchangeable.

#CSV File Operations-

A CSV file(comma separated value file) is a type of plain text file that uses specific structuring to arrange tabular forms of data. Because it’s a plain text file so it only contains actual text data. If you want to read data then reader function is used. This function takes each row of the file and make a list of all columns. Then you have to choose column you want variable data for. For writing you need to use writer function.

#user define functions and in-built functions-

A function that you define yourself in program is basically a user-defined functions. You can use any name to a user-defined functions. We can’t take the keyword as python. For defining this function we use def as a keyword. Built-in functions are basically provided by the language itself that is it’s a part of the high level language which can be executed by a simple reference with specifying the arguments.

#global and local variables-

A variable which is declared outside of the function is known as global variable. It means that this variable can be accessed inside or outside of the function. A local variable is declared within the function or is an argument passed to a function. So it states that this function can be used only within that function itself.

#lambda, map, filter and reduce-

Lambda function is a single line function declared with no name, which can have any number of arguments, but it has only one expression. Map function returns a map object(which is iterator) of the results after applying the given function to each item of a given iterable(list, tuple etc ). Filter method filters the given sequence with help of function that tests each elements in that sequence. Reduce function is used to apply a particular function passed in its arguments to all the list elements mentioned in the sequence.

#python queue-

Like stack, queue is a linear data structure that stores items in first in first out manner. With a queue the least recently added item is removed first. For example consumers for a resource where the consumer that came first is served first. Operation includes rear, front, dequeue, enqueue. It can be implemented by list, collections.deque and queue.queue.

#zip function-

This function returns a zip object, which is an iterator of tuples where the first item in each passed iterator is paired together, and then the second item in each passed iterator are paired together etc. If the passed iterators have different lengths, then the iterator with the least items decides the length of new iterator.

# concept of recursion and iterator-

Recursion is a common mathematical and programming concept. It means that a function calls itself. This has the benefit of meaning that you can loop through data to reach a result. Iterator is simply a object that can be iterated upon or contains a countable number of values. In technically, its an object which implements the iterator protocol, which consist of methods __iter__() and __next__().

#generator and decorators-

Generators are used to create iterators, but with different approach. Generators are simple function which returns an iterable set of items, one at a time. This function can generate as many values as it wants. Decorators are very powerful tool since it allows programmers to modify the behavior of function or class. In this functions are taken as the argument into another function and then called inside the wrapper function.

#isinstance, use of format, timeit()-

The isinstance function returns true if the specified object is of the specified type, otherwise false. For example if the type parameter is a tuple, this function will return true if the object is one of the types in the tuple. The format method formats the specified values and insert them inside the string placeholder. the format method returns the formatted string. Timeit module provides a simple way to find the execution time of small bits of python code.it has both a command-line interface and a callable one.

#numpy official site-

There are some websites which you can refer for numpy. For example numpy.org. So for easy learning there is a QuickStart which resides in this org website only. Its too useful and explanation is up to the mark.

#scipy official site-

In this video, you will see which websites you need to use and get used to it. For example scipy.org. This website is too useful and you can learn many things from that.