Tuples in Python

In this article, we will see what are Tuple and how we use them in Python programming.

Tuples:

 

Tuples are one of the built-in types of sequences out of six and just like lists. There is another article published on how to use Lists in Python. We want to store the values for the rest of our program then we can use Tuples.  Now for an example, if we want to store the name of some category of any Test plan when comes to compliance like “Audit, SOX, Risk Management or ORM” for continuing some program.

First, we need to declare a tuple and give it a name, the initial values will be used within parentheses “()”. All the values will be separated by a comma………continue reading from my original article that was published on Experts-Exchange.com and provides a basic explanation on how to use Tuples in Python programming language.

 

Thank you for reading my blog, the reference is taken from one of my article that was published by Experts-Exchange.

Please feel free to leave me some feedback or to suggest any future topics.

Looking forward to hearing from you – Swadhin Ray (Sloba) -( LinkedIn ) ( Twitter )

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Logical Operators in Python

In this article, we will see what is the logical operator and how we use them in Python programming.

Logical Operators:

There are basically three types of logical operators as below:

  • And
  • Or
  • Not

There above operators semantics or meaning is the same as their meaning in English.  To demonstrate we can take one simple example like a number can be greater then 2 and less then 5, so if we consider this example then we know that there could be only two possible numbers comes in between i.e. 3 and 4. So now let us run this example and verify the results by passing different numbers……….continue reading from my original article that was published on Experts-Exchange.com and provides a basic explanation on how to use Logical Operators in Python programming language.

 

Thank you for reading my blog, the reference is taken from one of my article that was published by Experts-Exchange.

Please feel free to leave me some feedback or to suggest any future topics.

Looking forward to hearing from you – Swadhin Ray (Sloba) -( LinkedIn ) ( Twitter )

Boolean in Python

In this article, we will see how to use Boolean in Python where it can be used to take any decisions if it is true or false, yes or no,  1 or 0.

What is Boolean?

It is just an integer that can have 1, 0,-1 or floats like 0.32, 3.32 etc. The output of the decisions can be true or false.

In many cases during writing code or implementing any comparison to consider any decision we usually use boolean in any programming language.  ………continue reading from my original article that was published on Experts-Exchange.com and provides a basic explanation on how to use Boolean in Python programming language.

 

Thank you for reading my blog, the reference is taken from one of my article that was published by Experts-Exchange.

Please feel free to leave me some feedback or to suggest any future topics.

Looking forward to hear from you – Swadhin Ray (Sloba) -( LinkedIn ) ( Twitter )

Using Break condition in Python

This article will show a step by step guide on how use Break in Python

In many use cases, or due to certain business rules, we need to exit a loop in any programming language. Or, we need to stop a particular loop and continue with the rest of the code.

This article will help you to understand the use of a break in Python which is mainly used to exit the loops in python programming.

To achieve this we need to use “break” keyword while running a loop.

Let’s take a very simple example of how to use a break in Python programming language.

Example :

j= 1
for i in range (6):
j=j*2
print ('i= ',i, 'j=',j)
if j==32:
break

Open in new window

If we execute the above code in any Python interpreter, then we will see the following result :

So let’s try to understand the code without adding the break statement.

j= 1
for i in range (6):
j=j*2
print ('i= ',i, 'j=',j)
 

Open in new window

Now we see the code execute without any break. The loop starts from 1 till 5 as we have provided the range as “6” so starting from 0 till 5 the loop will execute :

If we compare the code with a break keyword, we have given an argument as if the result of “j” will be 32, then end the execution of the code so that the loop will run till range 5, as at this point the result of “j” is “32”.

This article was to explain and show you a simple programme on how to use a break statement in Python. I hope I’ve achieved just that.

Thank you for reading my blog, the reference is taken from one of my article that was published by Experts-Exchange.

Please feel free to leave me some feedback or to suggest any future topics.

Looking forward to hear from you – Swadhin Ray (Sloba) -( LinkedIn ) ( Twitter )

Append row into a CSV file on SFTP

In this post I am going to show how we can append a row into CSV file using simple bash command.

To demonstrate this I am using Linux virtual machine, the OS is on Mint 18.3 64bit.  First me create a sample file on my Linux Machine as like below.

dev@dev-VirtualBox ~/Desktop/CSV $ pwd
/home/dev/Desktop/CSV
dev@dev-VirtualBox ~/Desktop/CSV $ ls
dev@dev-VirtualBox ~/Desktop/CSV $ cat <<EOF >sample.csv
> COL1,COL2,COL3
> 1,FIRST_LINE,18-JAN-2018
> EOF
dev@dev-VirtualBox ~/Desktop/CSV $ ls
sample.csv
dev@dev-VirtualBox ~/Desktop/CSV $

Once the file is created it will look something like below:

image

Now let us think that this file is on a SFTP server where we need to connect and append another line without renaming or changing the file format.

Login to the server


login as: dev
dev@10.0.0.203's password:
Welcome to Linux Mint 18.3 Sylvia (GNU/Linux 4.10.0-38-generic x86_64)

* Documentation:  <a href="https://www.linuxmint.com/">https://www.linuxmint.com</a>
Last login: Tue Jan 23 09:55:52 2018 from 10.0.0.203
dev@dev-VirtualBox ~ $ ls
Desktop  Documents  Downloads  Music  Pictures  Public  Templates  Videos
dev@dev-VirtualBox ~ $ cd Desktop/
dev@dev-VirtualBox ~/Desktop $ ls
CSV
dev@dev-VirtualBox ~/Desktop $ cd CSV/
dev@dev-VirtualBox ~/Desktop/CSV $ ls
sample.csv

So now we can login to the server.

Method 1: Now let us execute the below line to insert or append a new row to the existing CSV file i.e. sample.csv:


dev@dev-VirtualBox ~/Desktop/CSV $ sed -i.bak 1i"2,Second_Line,18-JAN-2018" sample.csv
dev@dev-VirtualBox ~/Desktop/CSV $

Once the above line is executed we will see the row is inserted but not at the end but at the beginning.

image

Now how we can append the line at the end .


dev@dev-VirtualBox ~/Desktop/CSV $ pwd
/home/dev/Desktop/CSV
dev@dev-VirtualBox ~/Desktop/CSV $ ls
sample.csv
dev@dev-VirtualBox ~/Desktop/CSV $ cat sample.csv
COL1,COL2,COL3
1,FIRST_LINE,18-JAN-2018
dev@dev-VirtualBox ~/Desktop/CSV $ sed -i -e "\$a2,Second_Line,18-JAN-2018" sample.csv
dev@dev-VirtualBox ~/Desktop/CSV $ cat sample.csv
COL1,COL2,COL3
1,FIRST_LINE,18-JAN-2018
2,Second_Line,18-JAN-2018
dev@dev-VirtualBox ~/Desktop/CSV $

 

The line used to insert the row/ append the row at the end is :

sed -i -e "\$a2,Second_Line,18-JAN-2018" sample.csv

Method 2: Now let us check how we can use echo to insert the line at the end.


dev@dev-VirtualBox ~/Desktop/CSV $ echo "3,Third_Line,18-JAN-2018" >> sample.csvdev@dev-VirtualBox ~/Desktop/CSV $ cat sample.csv
COL1,COL2,COL3
1,FIRST_LINE,18-JAN-2018
2,Second_Line,18-JAN-2018
3,Third_Line,18-JAN-2018
dev@dev-VirtualBox ~/Desktop/CSV $

Method 3: Append using a simple python programming


dev@dev-VirtualBox ~/Desktop/CSV $ python
Python 2.7.12 (default, Nov 19 2016, 06:48:10)
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> with open('sample.csv', 'a') as file:
...     file.write('4,Fourth_Line,18-JAN-2018')
... ;
   File "<stdin>", line 3
     ;
     ^
SyntaxError: invalid syntax
>>> with open('sample.csv', 'a') as file:
...     file.write('4,Fourth_Line,18-JAN-2018\n');
...
>>> exit()

Finally, the file will look like as below:


dev@dev-VirtualBox ~/Desktop/CSV $ cat sample.csv
COL1,COL2,COL3
1,FIRST_LINE,18-JAN-2018
2,Second_Line,18-JAN-2018
3,Third_Line,18-JAN-2018
4,Fourth_Line,18-JAN-2018

dev@dev-VirtualBox ~/Desktop/CSV $



 

image

 

To automate the process you can create a script and try to pass the row as a input to the file while calling the script.

 

Thank you for reading my blog , please feel free to leave me some feedback or to suggest any future topics.

Looking forward to hear from you – Swadhin Ray (Sloba) -( LinkedIn ) ( Twitter )

 

Reorder the columns in CSV file using Python

Many time we work on files to load or process the flat files. In this post, I am showing if we receive the file but the columns are not in order then how to rearrange them in the right format. There are multiple ways to handle this but here I am using a simple python code which will reorder my columns.

Say for example my right order of my file should be as below:

 empno, ename, sal 

But say I receive a file with

 sal, ename, empno 

image

Now here is the simple python script which will change the file into right order :

import csv

with open('file2.csv', 'r') as infile, open('file2_modified.csv', 'a') as outfile:
fieldnames = ['empno','ename','sal']
writer = csv.DictWriter(outfile, fieldnames=fieldnames)
writer.writeheader()
for row in csv.DictReader(infile):
writer.writerow(row)

Save the above code as “target_file_format.py” or anyname you want.

Execute the python script , and check the result.

image

You can modify the code in various ways as per your need.

Thank you for reading my blog , please feel free to leave me some feedback or to suggest any future topics.

Looking forward to hear from you – Swadhin Ray (Sloba) -( LinkedIn ) ( Twitter )

For and While Loops in Python

When we want to run, execute or repeat a statement multiple times, a loop is necessary. This article covers the two types of loops in Python: the while loop and the for loop.

In python there are two types of loops: 

  • While loop
  • For loop

When we want to run or execute a piece of code multiple times sequentially, this requires a “for loop”, but there is another alternative called a “while loop”. The while loop can only be used when a specific condition is met, or to execute the code for n number of times—or without having a stop.

The While Loop

Let us try to understand the logic of the while loop. Let’s say a person hits a target using his bow till all the arrows are used up. In this case, as long as the container has an arrow in it, the person will take the arrow and hit the target using his bow.
Let’s assume the number of arrows in the container is 10. The target can be shot as long as the number of arrows is greater than zero. The final step would be to put the bow down when all the arrows have been shot.  So basically, as long as the arrows are present in the container, the loop of hitting the target using the bow will continue.  The logic of the while loop is: as long as the condition is true the loop continues.
Format of while loop in Python:

while <<expression>>:
    statements 
    ....
    ....

 

The while loop starts with the keyword “while” as shown in the above snippet. In the expression, we can use any condition that we want to make it true till we want the loop to be executed—followed by a colon.  Next, there could be one or more statements, but a tab is required before any statement. There is one important thing we need to keep in mind: if in any case the expression never becomes false, then the while loop will never stop, making it an “infinite loop”. In this case, the program will never end.
Now let us convert the example into a proper Python program. 

no_of_arrows = 10
while no_of_arrows > 0 :
	no_of_arrows = no_of_arrows -1
	print ("Number of arrows left in the container" + str(no_of_arrows))
print ("All arrows in the container is over and while loop completed")

 

Here is the output we get:

 

>>> 
============ RESTART: C:/Users/swadhin.ray/Desktop/While_loop.py ============
Number of arrows left in the container 9
Number of arrows left in the container 8
Number of arrows left in the container 7
Number of arrows left in the container 6
Number of arrows left in the container 5
Number of arrows left in the container 4
Number of arrows left in the container 3
Number of arrows left in the container 2
Number of arrows left in the container 1
Number of arrows left in the container 0
All arrows in the container is over and while loop completed
>>> 

 

The Python program automatically determines the end of the “while” when the Python interpreter finds a statement that is not tabbed. We don’t have to explicitly define it.

 

The For Loop:

When any string or list is iterated in sequence, this requires a for loop.
Here is a simple example to list the letters of a word using a for loop in python.

 

for x in 'apple':
     print ('Lits of letters in apple :',x)
print ("Apple letter over!")

 

The result will be as shown below:

 

============= RESTART: C:/Users/swadhin.ray/Desktop/for_loop.py =============
Lits of letters in apple : a
Lits of letters in apple : p
Lits of letters in apple : p
Lits of letters in apple : l
Lits of letters in apple : e
Apple letter over!
>>> 

 

Now say for example we have a list which has a few names and we want to loop it.

names = ['Ray', 'Mike',  'David']
for j in names:        
   print ( j , ' is a name')

The above code will print the below result or output:

 

============= RESTART: C:/Users/swadhin.ray/Desktop/for_loop.py =============
Ray  is a name
Mike  is a name
David  is a name
>>> 

 

Thank you for reading my blog , the reference is taken from one of my article that was published by Experts-Exchange.

Please feel free to leave me some feedback or to suggest any future topics.

Looking forward to hear from you – Swadhin Ray (Sloba) -( LinkedIn ) ( Twitter )