Python zip_longest() Function.

Shaila B — Fri, 30 Jul 2021 11:31:54 +0000

Consider if we have two iterators of different lengths. then we iterate them together one iterator must end up with another iterator.

OUTPUT:

Here the elements 5 and 6 are missing. Because the zip() function will stop aggregating once the shortest iterable passed to it is exhausted.

It will make more sense if we would return a group that containing elements 5 and 6 otherwise it will be problematic.

In this situation, we can use zip_longest().

The python zip_longest() function can fill up the position of empty iterable with some user-defined values.

If the user does not define the fillvalue parameter, the zip_longest() function fills None as the default value.

For Example :

OUTPUT:

In the above example, we imported zip_longest() function from itertools library.

We can observe in the above example those list y elements are filled with no value.

OUTPUT:

In the above example, list y elements fill with integer value as 1.

OUTPUT:

In the above example list y elements filled with float value as 1.5

OUTPUT:

In the above example list y is filled with a string value as 'Explore'.

OUTPUT:

In the above example list y is filled with boolean value True.

Python zip() Function.

Shaila B — Thu, 29 Jul 2021 13:37:48 +0000

Python zip() function :

zip() function. It is used when there are two or more iterables and they need to be aggregated into one iterable.

(or)

zip() method is to map the similar index of multiple containers so that they can be used just using as a single entity.

Syntax : zip(*iterators)

For references see the example below:

list1 = [1, 2, 3, 4]

list2 = [5, 6, 7, 8]

result = list(zip(list1, list2))

print(result)

OUTPUT:

[(1, 4), (2, 5), (3, 6)]

When two lists have an equal number of elements, 3rd list with elements from both lists can be created using zip().

list1 = [1, 2, 3]

list2 = [4, 5, 6]

Here the list1 and list2 have an equal number of elements. The result list contains the list1 and list2 elements.

result = list(zip(list1, list2))

print(result)

OUTPUT:

[(1, 4), (2, 5), (3, 6)]

When two lists have an equal number of elements, we can create a dictionary with these elements, the elements of the first list will be considered as keys and the elements of the second list will be considered as values.

For example :

list1 = [1, 2, 3]

list2 = [4, 5, 6]

result = dict(zip(list1, list2))

print(result)

OUTPUT:

{1: 4, 2: 5, 3: 6}

Let's see some more examples below

Creating a list using columns and values or data.

columns = ['employee_id', 'employee_name', 'employee_salary']

values = [1, 'John', '50000']

employee_details = list(zip(columns, values))

print(employee_details)

OUTPUT:

[('employee_id', 1), ('employee_name', 'John'), ('employee_salary', '50000')]

Creating a dictionary using columns and values.

columns = ['employee_id', 'employee_name', 'employee_salary']

values = [1, 'Smith', 80000]

employee_details = dict(zip(columns, values))

print(employee_details)

OUTPUT:

{'employee_id': 1, 'employee_name': 'Smith', 'employee_salary': 80000}

We can apply zip() on tuples.

columns = ('employee_id', 'employee_name', 'employee_salary')

values = (1, 'Eshani', 50000)

employee_details = dict(zip(columns, values))

print(employee_details)

OUTPUT:

{'employee_id': 1, 'employee_name': 'Eshani', 'employee_salary': 50000}

zip() function for multiple data.

columns = ('employee_id', 'employee_name', 'employee_salary')

values = (
    (1, 'John', 50000),
    (2, 'Smith', 80000),
    (3, 'Ruhi', 60000),
    (4, 'Arnav', 50000),

)

In the above, we have multiple employee data so here we are going to use list comprehension

We need to apply zip on each record to create a list of dictionaries. Example using list comprehensions. We are applying zip and then dictionary on each employee.

employee_details = [list(zip(columns, employee)) for employee in values]

print(employee_details)

OUTPUT:

[[('employee_id', 1), ('employee_name', 'John'), ('employee_salary', 50000)], [('employee_id', 2), ('employee_name', 'Smith'), ('employee_salary', 80000)], [('employee_id', 3), ('employee_name', 'Ruhi'), ('employee_salary', 60000)], [('employee_id', 4), ('employee_name', 'Arnav'), ('employee_salary', 50000)]]

We can use dictionary comprehension.

columns = ('employee_id', 'employee_name', 'employee_salary')

values = [
          (1, 'Teena', 80000),
          (2, 'Mouna', 60000),
          (3, 'Janvi', 40000),

         ]


employees_details = [dict(zip(columns, employee)) for employee in values]

print(employees_details)

OUTPUT:

[{'employee_id': 1, 'employee_name': 'Teena', 'employee_salary': 80000}, {'employee_id': 2, 'employee_name': 'Mouna', 'employee_salary': 60000}, {'employee_id': 3, 'employee_name': 'Janvi', 'employee_salary': 40000}]

Using the map as we are trying to apply a row-level transformation to convert each employee into the dictionary with columns as keys.

columns = ('employee_id', 'employee_name', 'employee_salary')

values = [
          (1, 'John', 50000),
          (2, 'Smith', 80000),
          (3, 'Sanvi', 60000)
         ]

employee_details = list(map(lambda employee: dict(zip(columns, employee)), values))

print(employee_details)

OUTPUT:

[{'employee_id': 1, 'employee_name': 'John', 'employee_salary': 50000}, {'employee_id': 2, 'employee_name': 'Smith', 'employee_salary': 80000}, {'employee_id': 3, 'employee_name': 'Sanvi', 'employee_salary': 60000}]

Printing data type of the first element employees_list

print(employee_details[0])

OUTPUT:

{'employee_id': 1, 'employee_name': 'John', 'employee_salary': 50000}

Printing size of employees_list

print(len(employee_details))

OUTPUT:

Write your own web server in python.

Shaila B — Thu, 22 Jul 2021 19:46:39 +0000

In python, there are libraries that allow you to write your own web server in a few lines.

For Example:

When you run this, your machine will listen on port 8000 for requests.

In a web browser, If you navigate to http://127.0.0.1:8000/

The browser will get the response as below

Let’s learn about the special variable name in python.

Shaila B — Sat, 03 Jul 2021 08:08:31 +0000

In python, there is no main() function. When we run a python program, the code is given to the interpreter, then the given code is to be executed at the level 0 indentation, before doing that it will define a few special variables. name is one such special variable. name is a special variable that will store the current module name.
Syntax : name

DEV Community: Shaila B

Python zip_longest() Function.

Python zip() Function.

Python zip() function :

Let's see some more examples below

Write your own web server in python.

Let’s learn about the special variable __name__ in python.

Let’s learn about the special variable name in python.