Replace String in Python

 

At times we need to replace strings in a statement or in a file. We will see here how we can replace a string with another in python.

To Replace a string in python, we can user replace() method.

Example: 

        old_string = "This is the old string."

        new_string = old_string.replace("old", "new")

        print(new_string)

This can also be achieved by using the 're' module of python, which is used for advanced string and regex replacements.

Code: 

    

        import re

        old_string = "This is the old string."

        new_string = re.sub("old", "new", old_string)

        print(new_string)

        Output: This is the new string.

PowerShell: Check if the entered number is a valid Binary and print its decimal value

Powershell Script Description: 

Pass a number to a PowerShell script as an argument and validate whether it is a valid Binary. If the entered number is a valid binary, display its decimal value.

Script: isValidBinary.ps1

if (  $args[0] ){

    $num = $args[0]

    try {

        $value = [convert]::ToInt32(“$num”,2)

        Write-Host "'$num' is a valid Binary" -ForegroundColor Green

        Write-host "Decimal Value: $value"

        }

    catch{

        Write-Host  "'$num' is not a valid Binary" -ForegroundColor Red

    }

}

else{

    Write-Host "You must pass a number to the script"

}

Output:

 

Shell Script that accepts a positive integer and returns comma separated list of integers in descending order

Description: 

Write a  shell script that accepts exactly 1 argument which must be a positive integer. 

The script will print a comma-separated list of integers, all on the same line in descending order

Script: decreaseNum.sh

 

#!/bin/bash

#-----------------------------------------------

#user input

num=$1

temp=''

         

        #continue while input is greater than 0
 while [ $num -gt 0 ]
 do

                #append the numbers in decreasing order with comma-separated
  temp+="$num, "
  num=$(( $num - 1 ))
    done
 temp=$(echo $temp | sed 's/,$//')

 echo $temp

Output:

Shell Script: Get the Average Grade of a Student

Write a shell script, which gives back the average grade of a student The student name we should give as a parameter! If you give a name that is not in the data file, please write out an error message and write out the list of the names (Just the names without the grades!!!) as a help!

input file: class.txt

Name/Math Informatics Literature English
Mohammed 3 4 5 4
Alan 2 1 3 2
Li 3 5 1 3
Jane 4 2 3 1

SCRIPT:

#!/bin/bash

# Variable Declaration
input_file="./class.txt"
name=$1
average=0
err_msg="\n\tPlease pass a student name to the script. \n\te.g.: ./average.sh Tom \n" 
name_list=`cat class.txt | awk '(NR != 1) {print $1}' | tr "\n" ","  | sed -e 's/,$//' -e 's/,/, /g' `
#---------------------------------------------------------------------------------------------
if [ -z "$name" ]
then
echo -e "$err_msg"
else
record=$(grep -w "$name" $input_file)
if [ -n "$record" ]
then
#sum=$(echo $a | awk '{sum=0; for (i=2; i<=NF; i++) { sum +=i} print sum }')
average=$(echo $record | awk '{sum=0; for (i=2; i<=NF; i++) { sum +=$i} print sum/(NF - 1) }')
echo -e "\t $name $average \n"
else
echo -e "No $name is in the list. There are: $name_list"
fi
fi

let's check the output: