How to remove values from one vector that exist in another vector

2.56 How to remove values from one vector that exist in another vector

2.56.1 Mathematica
2.56.2 Matlab
2.56.3 Fortran
2.56.4 Maple

Given vector \(v1=\{1,3,4,5,8,9,20.2,30,-44\}\) remove from it any element that exist in \(v2=\{1,7,4\}\). Notice that Complement[] in Mathematica or setdiff() in Matlab can be used, but they will sort the result. Hence they are not used here in order to keep the order the same.

2.56.1 Mathematica

#first method 
v1={1,3,4,5,8,9,20.2,30,-44}; 
v2={1,7,4}; 
v1=DeleteCases[v1,Alternatives@@v2]

{3,5,8,9,20.2,30,-44}

#second method 
v1={1,3,4,5,8,9,20.2,30,-44}; 
v2={1,7,4}; 
v1=DeleteCases[v1,x_/;MemberQ[v2,x]]

{3,5,8,9,20.2,30,-44}

2.56.2 Matlab

v1=[1,3,4,5,8,9,20.2,30,-44]; 
v2=[1,7,4]; 
v1(ismember(v1,v2))=[]

v1 = 
3.0000 5.0000 8.0000 9.0000 20.2000 30.0000 -44.0000

2.56.3 Fortran

program f  implicit none 
  REAL, ALLOCATABLE :: A(:),B(:) 
  A =[1.0,3.0,4.0,5.0,8.0,9.0,20.2,30.0,-44.0]; 
  B =[1.0,7.0,4.0]; 
  A = pack(A, A .NE. B) 
  Print *,A 
end program f

>gfortran f2.f90 
>./a.out 
3.0000000 5.0000000 8.0000000  9.0000000  20.200001  30.000000 -44.000000

2.56.4 Maple

v1:=Array([1,3,4,5,8,9,20.2,30,-44]); 
v2:=Array([1,7,4]); 
select[flatten](x->not(member(x,v2)),v1)

[3, 5, 8, 9, 20.2, 30, -44]

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