Coding Bash vs. Perl vs. Python (by Evan Liu)

Topics about set

Set: Check membership of a value in a set 

In Bash, set data structure is not support , however in bash 4, associative array can be used to simulate set

In Perl, there is no native data type for set too, we can use hash with dummy value or some cpan modules such as Set::Scalar instead.

In Python, set is supported well. 

Tasks:
1.Create a set from elements with duplicates
2.Print the set
3.Check the membership of '0'
Bash Perl Python 
  1. #1.Create a set from elements with duplicates

  2. arr=(0 2 4 6 8 2 4 6)

  3. declare -A set1

  4. for i in "${arr[@]}"; do set1[$i]=1; done

  5. 

  6. #2.Print the set

  7. #  use 'declare -p' to print

  8. declare -p set1

  9. #  or use for loop

  10. for i in "${!set1[@]}"; do echo -n "$i "; done; echo

  11. 

  12. #3.Check the membership of '0'

  13. [ -n "${set1[0]}" ] && echo "found 0 in set"

  14. 

  15. 

  16. -------output----------

  1. #1.Create a set from elements with duplicates

  2. 

  3. #2.Print the set

  4. #  use 'declare -p' to print

  5. declare -A set1='([0]="1" [2]="1" [4]="1" [6]="1" [8]="1" )'

  6. #  or use for loop

  7. 0 2 4 6 8 

  8. 

  9. #3.Check the membership of '0'

  10. found 0 in set

  1. use feature ":5.10";

  2. #1.Create a set from elements with duplicates

  3. @lst=(0,2,4,6,8,2,4,6);

  4. %set1 = map { $_ => 1 } @lst;

  5. 

  6. #2.Print the set

  7. say keys %set1;

  8. 

  9. #3.Check the membership of '0'

  10. $set1{0} and say "found 0 in set";

  11. 

  12. -------output----------

  1. #1.Create a set from elements with duplicates

  2. 

  3. #2.Print the set

  4. 60284

  5. 

  6. #3.Check the membership of '0'

  7. found 0 in set

  1. #1.Create a set from elements with duplicates

  2. set1 = set([0,2,4,6,8,2,6])

  3. 

  4. #2.Print the set

  5. print set1

  6. #  or use curly braces to define

  7. set2 = {0,2,4,6,8,2,6}

  8. print set2

  9. 

  10. #3.Check the membership of '0'

  11. if 0 in set1: print "found 0 in set"

  12. 

  13. -------output----------

  1. #1.Create a set from elements with duplicates 

  2. 

  3. #2.Print the set 

  4. set([0, 8, 2, 4, 6])

  5. #  or use curly braces to define 

  6. set([8, 0, 2, 4, 6])

  7. 

  8. #3.Check the membership of '0' 

  9. found 0 in set

Set: Add or remove a member in set 


		  
		  

		  
Tasks:
1.Create a set
2.Add a new element '10'
3.delete the new element '10'
		  

		       
          
          

             
             

		     

                Bash
                Perl
                Python			   
		     

             
              

                
  1. #1.Create a set

  2. declare -A set1='([0]="1" [2]="1" [4]="1" [6]="1" [8]="1" )'

  3. 

  4. #2.Add a new element '10'

  5. set1[10]="1"

  6. declare -p set1

  7. 

  8. #3.delete the new element '10'

  9. unset set1[10]

  10. declare -p set1

  11. 

  12. -------output----------



  1. #1.Create a set

  2. 

  3. #2.Add a new element '10'

  4. declare -A set1='([10]="1" [0]="1" [2]="1" [4]="1" [6]="1" [8]="1" )'

  5. 

  6. #3.delete the new element '10'

  7. declare -A set1='([0]="1" [2]="1" [4]="1" [6]="1" [8]="1" )'



                
  1. #1.Create a set

  2. %set1 = map { $_ => 1 }(0,2,4,6,8);

  3. 

  4. #2.Add a new element '10'

  5. $set1{10}=1;

  6. print "$_ " foreach(keys %set1);

  7. 

  8. #3.delete the new element '10'

  9. delete $set1{10};

  10. print "$_ " foreach(keys %set1);

  11. 

  12. -------output----------



  1. #1.Create a set

  2. 

  3. #2.Add a new element '10'

  4. 8 10 6 4 2 0 #3.delete the new element '10'

  5. 8 6 4 2 0



                
  1. #1.Create a set

  2. set1 = set([0,2,4,6,8])

  3. 

  4. #2.Add a new element '10'

  5. set1.add(10)

  6. print set1

  7. 

  8. #3.delete the new element '10'

  9. set1.remove(10)

  10. print set1

  11. #  or use discard(), which will not throw error if membership not found

  12. set1.discard(9)

  13. set1.discard(8)

  14. print set1

  15. 

  16. -------output----------



  1. #1.Create a set 

  2. 

  3. #2.Add a new element '10' 

  4. set([0, 2, 4, 6, 8, 10])

  5. 

  6. #3.delete the new element '10' 

  7. set([0, 2, 4, 6, 8])

  8. #  or use discard(), which will not throw error if membership not found 

  9. set([0, 2, 4, 6])



              

             
            
 
          

          

		  

        
          

		  
Set: Copy a set 

		  
In Bash4
Copying associative arrays is not directly possible

		  
		  

		  
Tasks:
1.Create a set named set1
2.Copy set1 to set2
3.Empty set1 then print it
4.print set2
		  

		       
          
          

             
             

		     

                Bash
                Perl
                Python			   
		     

             
              

                
  1. #1.Create a set named set1

  2. declare -A set1='([0]="1" [2]="1" [4]="1" [6]="1" [8]="1" )'

  3. 

  4. #2.Copy set1 to set2

  5. tmpstr=$(declare -p set1)

  6. eval "declare -A set2="${tmpstr#*=}

  7. declare -p set2

  8. 

  9. #3.Empty set1 then print it

  10. unset set1

  11. declare -p set1 2>/dev/null

  12. 

  13. #4.print set2

  14. declare -p set2

  15. 

  16. -------output----------



  1. #1.Create a set named set1

  2. 

  3. #2.Copy set1 to set2

  4. declare -A set2='([0]="1" [2]="1" [4]="1" [6]="1" [8]="1" )'

  5. 

  6. #3.Empty set1 then print it

  7. 

  8. #4.print set2

  9. declare -A set2='([0]="1" [2]="1" [4]="1" [6]="1" [8]="1" )'



                
  1. #1.Create a set named set1

  2. %set1 = map { $_ => 1 }(0,2,4,6,8);

  3. 

  4. #2.Copy set1 to set2

  5. %set2 = %set1;

  6. 

  7. #3.Empty set1 then print it

  8. map { delete $set1{$_} } keys %set1;

  9. print "$_ " foreach(keys %set1);

  10. 

  11. #4.print set2

  12. print "$_ " foreach(keys %set2);

  13. 

  14. -------output----------



  1. #1.Create a set named set1

  2. 

  3. #2.Copy set1 to set2

  4. 

  5. #3.Empty set1 then print it

  6. 

  7. #4.print set2

  8. 6 0 2 8 4



                
  1. #1.Create a set named set1

  2. set1 = set([0,2,4,6,8])

  3. 

  4. #2.Copy set1 to set2

  5. #  set2 is only a pointer to set1

  6. set2 = set1

  7. #  do a shallow copy to set3

  8. set3 = set1.copy()

  9. 

  10. #3.Empty set1 then print it

  11. set1.clear()

  12. print set1

  13. 

  14. #4.print set2

  15. print set2

  16. #  print set3

  17. print set3

  18. 

  19. -------output----------



  1. #1.Create a set named set1 

  2. 

  3. #2.Copy set1 to set2 

  4. #  set2 is only a pointer to set1 

  5. #  do a shallow copy to set3 

  6. 

  7. #3.Empty set1 then print it 

  8. set([])

  9. 

  10. #4.print set2 

  11. set([])

  12. #  print set3 

  13. set([0, 8, 2, 4, 6])



              

             
            
 
          

          

		  

        
          

		  
Set: Get intersection of two sets 

		  

		  
		  

		  
Tasks:
1.Create two sets
2.Get intersection of the two sets
		  

		       
          
          

             
             

		     

                Bash
                Perl
                Python			   
		     

             
              

                
  1. #1.Create two sets

  2. declare -A set1='([0]="1" [2]="1" [4]="1" [6]="1" [8]="1" )'

  3. declare -A set2='([0]="1" [3]="1" [6]="1" [9]="1" )'

  4. 

  5. #2.Get intersection of the two sets

  6. oldIFS=$IFS IFS=$'\n\t'

  7. arri=($(comm -12  <(echo "${!set1[*]}"|sort) <(echo "${!set2[*]}"|sort)))

  8. IFS=$oldIFS

  9. declare -A seti

  10. for i in "${arri[@]}"; do seti[$i]=1; done

  11. declare -p seti

  12. 

  13. 

  14. -------output----------



  1. #1.Create two sets

  2. 

  3. #2.Get intersection of the two sets

  4. declare -A seti='([0]="1" [6]="1" )'



                
  1. #1.Create two sets

  2. %set1 = map { $_ => 1 }(0,2,4,6,8);

  3. %set2 = map { $_ => 1 }(0,3,6,9);

  4. 

  5. #2.Get intersection of the two sets

  6. #  for each $_ in %set1, lookup it in $set2, if found,it's eligable

  7. %seti = map { $_ => 1 } grep { $set2{$_} } keys %set1;

  8. print "$_ " foreach(keys %seti);

  9. 

  10. 

  11. -------output----------



  1. #1.Create two sets

  2. 

  3. #2.Get intersection of the two sets

  4. #  for each  in %set1, lookup it in , if found,it's eligable

  5. 6 0



                
  1. #1.Create two sets

  2. set1 = set([0,2,4,6,8])

  3. set2 = set((0,3,6,9))

  4. 

  5. #2.Get intersection of the two sets

  6. print set1 & set2

  7. #  or use intersection() function

  8. print set1.intersection(set2)

  9. 

  10. -------output----------



  1. #1.Create two sets 

  2. 

  3. #2.Get intersection of the two sets 

  4. set([0, 6])

  5. #  or use intersection() function 

  6. set([0, 6])



              

             
            
 
          

          

		  

        
          

		  
Set: Get difference of two sets 

		  

		  
		  

		  
Tasks:
1.Create two sets
2.Get difference of the two sets
		  

		       
          
          

             
             

		     

                Bash
                Perl
                Python			   
		     

             
              

                
  1. #1.Create two sets

  2. declare -A set1='([0]="1" [2]="1" [4]="1" [6]="1" [8]="1" )'

  3. declare -A set2='([0]="1" [3]="1" [6]="1" [9]="1" )'

  4. 

  5. #2.Get difference of the two sets

  6. oldIFS=$IFS IFS=$'\n\t'

  7. arrd=($(comm -23  <(echo "${!set1[*]}"|sort) <(echo "${!set2[*]}"|sort)))

  8. IFS=$oldIFS

  9. declare -A setd

  10. for i in "${arrd[@]}"; do setd[$i]=1; done

  11. declare -p setd

  12. 

  13. 

  14. -------output----------



  1. #1.Create two sets

  2. 

  3. #2.Get difference of the two sets

  4. declare -A setd='([2]="1" [4]="1" [8]="1" )'



                
  1. #1.Create two sets

  2. %set1 = map { $_ => 1 }(0,2,4,6,8);

  3. %set2 = map { $_ => 1 }(0,3,6,9);

  4. 

  5. #2.Get difference of the two sets

  6. #  for each $_ in %set1, lookup it in $set2, if not found,it's eligable

  7. %setd = map { $_ => 1 } grep { not $set2{$_} } keys %set1;

  8. print "$_ " foreach(keys %setd);

  9. 

  10. -------output----------



  1. #1.Create two sets

  2. 

  3. #2.Get difference of the two sets

  4. #  for each  in %set1, lookup it in , if not found,it's eligable

  5. 2 8 4



                
  1. #1.Create two sets

  2. set1 = set([0,2,4,6,8])

  3. set2 = set((0,3,6,9))

  4. 

  5. #2.Get difference of the two sets

  6. print set1 - set2

  7. #  or use difference() function

  8. print set1.difference(set2)

  9. 

  10. -------output----------



  1. #1.Create two sets 

  2. 

  3. #2.Get difference of the two sets 

  4. set([8, 2, 4])

  5. #  or use difference() function 

  6. set([8, 2, 4])



              

             
            
 
          

          

		  

        
          

		  
Set: Get union of two sets 

		  

		  
		  

		  
Tasks:
1.Create two sets
2.Get union of the two sets
		  

		       
          
          

             
             

		     

                Bash
                Perl
                Python			   
		     

             
              

                
  1. #1.Create two sets

  2. declare -A set1='([0]="1" [2]="1" [4]="1" [6]="1" [8]="1" )'

  3. declare -A set2='([0]="1" [3]="1" [6]="1" [9]="1" )'

  4. 

  5. #2.Get union of the two sets

  6. oldIFS=$IFS IFS=$'\n\t'

  7. arru=($(comm  <(echo "${!set1[*]}"|sort) <(echo "${!set2[*]}"|sort)))

  8. IFS=$oldIFS

  9. declare -A setu

  10. for i in "${arru[@]}"; do setu[$i]=1; done

  11. declare -p setu

  12. 

  13. 

  14. -------output----------



  1. #1.Create two sets

  2. 

  3. #2.Get union of the two sets

  4. declare -A setu='([0]="1" [2]="1" [3]="1" [4]="1" [6]="1" [8]="1" [9]="1" )'



                
  1. #1.Create two sets

  2. %set1 = map { $_ => 1 }(0,2,4,6,8);

  3. %set2 = map { $_ => 1 }(0,3,6,9);

  4. 

  5. #2.Get union of the two sets

  6. #  merge the two array from keys of set1 and set2

  7. %setu = map { $_ => 1 } keys %set1, keys %set2;

  8. print "$_ " foreach(keys %setu);

  9. 

  10. -------output----------



  1. #1.Create two sets

  2. 

  3. #2.Get union of the two sets

  4. #  merge the two array from keys of set1 and set2

  5. 0 2 8 6 4 3 9



                
  1. #1.Create two sets

  2. set1 = set([0,2,4,6,8])

  3. set2 = set((0,3,6,9))

  4. 

  5. #2.Get union of the two sets

  6. print set1 | set2

  7. #  or use union() function

  8. print set1.union(set2)

  9. 

  10. -------output----------



  1. #1.Create two sets 

  2. 

  3. #2.Get union of the two sets 

  4. set([0, 2, 3, 4, 6, 8, 9])

  5. #  or use union() function 

  6. set([0, 2, 3, 4, 6, 8, 9])