Generate and return a vector of unique values in the input array.
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Detailed Description

Generate and return a vector of unique values in the input array.

The uniqueness of the values can be optionally determined by the user by specifying the external input function that checks the equivalence of a pair of elements of the input array.

Parameters

[in]

array

: The input contiguous array of shape (:) of either

type character of kind any supported by the processor (e.g., SK, SKA, SKD , or SKU), or
type logical of kind any supported by the processor (e.g., LK), or
type integer of kind any supported by the processor (e.g., IK, IK8, IK16, IK32, or IK64), or
type complex of kind any supported by the processor (e.g., CK, CK32, CK64, or CK128), or
type real of kind any supported by the processor (e.g., RK, RK32, RK64, or RK128),

or,

a scalar assumed-length character of kind any supported by the processor (e.g., SK, SKA, SKD , or SKU),

whose unique elements are to be returned.

iseq

: The external user-specified function that takes two input scalar arguments of the same type and kind as the input array.
It returns a scalar logical of default kind LK that is .true. if the two input arguments are equivalent (e.g., equal) according to the user-defined criterion, otherwise, it is .false..
The following illustrates the generic interface of iseq,

function iseq(element1, element2) result(equivalent)
    use pm_kind, only: LK
    TYPE(KIND)  , intent(in)    :: element1, element2
    logical(LK)                 :: equivalent
end function

where TYPE(KIND) represents the type and kind of the input argument setA, which can be one of the following,

use pm_kind, only: SK, IK, CK, RK
character(*, SK), intent(in)    :: element1, element2 ! when `array` is a string vector.
character(1, SK), intent(in)    :: element1, element2 ! when `array` is a string scalar.
integer(IK)     , intent(in)    :: element1, element2
logical(LK)     , intent(in)    :: element1, element2
complex(CK)     , intent(in)    :: element1, element2
real(RK)        , intent(in)    :: element1, element2

where the kinds SK, IK, LK, CK, RK, can refer to any kind type parameter that is supported by the processor.
This user-defined equivalence check is extremely useful where a user-defined equivalence test other than exact equality or identity is needed, for example, when the array elements should match only within a given threshold or, when the case-sensitivity in character comparisons do not matter.
In such cases, the user can define a custom equivalence criterion within the user-defined external function iseq to achieve the goal.
(optional, the default equivalence operator is .eqv. if the input array is logical, otherwise ==.)

Returns: unique : The output allocatable array of the same type and kind as the input array containing all of its unique elements.

Possible calling interfaces ⛓

: use pm_arrayUnique, only: getUnique

unique = getUnique(array)

unique = getUnique(array, iseq)

pm_arrayUnique::getUnique
Generate and return a vector of unique values in the input array.
Definition: pm_arrayUnique.F90:2682

pm_arrayUnique
This module contains procedures and generic interfaces for finding unique values of an input array of...
Definition: pm_arrayUnique.F90:30

Warning: The pure procedure(s) documented herein become impure when the ParaMonte library is compiled with preprocessor macro CHECK_ENABLED=1.
By default, these procedures are pure in release build and impure in debug and testing builds.; The procedures under this generic interface are impure when the user-specified external procedure iseq is specified as input argument.; Note that in Fortran, trailing blanks are ignored in character comparison, that is, "Fortran" == "Fortran " yields .true..

Remarks: The functions under this generic interface are slightly slower than the setUnique subroutine implementations.

Note: If needed, use setSorted to sort the output unique values (in ascending order).

See also: getUnique
setUnique
isUniqueAll
isUniqueAny

Example usage ⛓

: 1program example

2

3 use pm_kind, only: LK

4 use pm_kind, only: SK ! All kinds are supported.

5 use pm_kind, only: IK ! All kinds are supported.

6 use pm_kind, only: CK ! All kinds are supported.

7 use pm_kind, only: RK ! All kinds are supported.

8 use pm_io, only: display_type

9 use pm_arrayUnique, only: getUnique

10

11 implicit none

12

13 character(:, SK), allocatable :: string_SK

14 character(9, SK), allocatable :: Array_SK(:) ! Can be any processor-supported kind.

15 integer(IK) , allocatable :: Array_IK(:) ! Can be any processor-supported kind.

16 complex(CK) , allocatable :: Array_CK(:) ! Can be any processor-supported kind.

17 real(RK) , allocatable :: Array_RK(:) ! Can be any processor-supported kind.

18

19 type(display_type) :: disp

20

21 disp = display_type(file = "main.out.F90")

22

23 call disp%skip()

24 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

25 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

26 call disp%show("! Find all unique elements in array.")

27 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

28 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

29 call disp%skip()

30

31 string_SK = "ParaMonte is a Monte Carlo Library."

32 Array_SK = ["ParaMonte", "PARAMONTE", "paramonte", "ParaMonte", "ParaMonte", "Paramonte"]

33 Array_IK = [1_IK, 1_IK, 4_IK, 4_IK]

34 Array_RK = [1._RK, 2._RK, 4._RK, 4._RK]

35 Array_CK = [(1._CK, -1._CK), (1._CK, -2._CK), (1._CK, -1._CK), (4._CK, -4._CK)]

36

37 call disp%skip()

38 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

39 call disp%show("! Unique elements in character scalar.")

40 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

41 call disp%skip()

42

43 call disp%show("string_SK")

44 call disp%show( string_SK, deliml = SK_"""" )

45 call disp%show("getUnique(string_SK)")

46 call disp%show( getUnique(string_SK), deliml = SK_"""" )

47

48 call disp%skip()

49 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

50 call disp%show("! Unique elements in character array.")

51 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

52 call disp%skip()

53

54 call disp%show("Array_SK")

55 call disp%show( Array_SK, deliml = SK_"""" )

56 call disp%show("getUnique(Array_SK)")

57 Array_SK = getUnique(Array_SK) ! This is a bug in gfortran as of version 11.

58 call disp%show( Array_SK, deliml = SK_"""" )

59

60 call disp%skip()

61 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

62 call disp%show("! Unique elements in integer array.")

63 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

64 call disp%skip()

65

66 call disp%show("Array_IK")

67 call disp%show( Array_IK )

68 call disp%show("getUnique(Array_IK)")

69 call disp%show( getUnique(Array_IK) )

70

71 call disp%skip()

72 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

73 call disp%show("! Unique elements in complex array.")

74 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

75 call disp%skip()

76

77 call disp%show("Array_CK")

78 call disp%show( Array_CK )

79 call disp%show("getUnique(Array_CK)")

80 call disp%show( getUnique(Array_CK) )

81

82 call disp%skip()

83 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

84 call disp%show("! Unique elements in real array.")

85 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

86 call disp%skip()

87

88 call disp%show("Array_RK")

89 call disp%show( Array_RK )

90 call disp%show("getUnique(Array_RK)")

91 call disp%show( getUnique(Array_RK) )

92

93 call disp%skip()

94 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

95 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

96 call disp%show("! Find all unique elements according to the user-specified equivalence criterion.")

97 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

98 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

99 call disp%skip()

100

101 call disp%skip()

102 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

103 call disp%show("! Unique elements in real array.")

104 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

105 call disp%skip()

106

107 Array_RK = [1.01_RK, 1.04_RK, 0.98_RK, 1.0_RK, 1.02_RK, 2._RK]

108

109 call disp%show("Array_RK")

110 call disp%show( Array_RK )

111 call disp%show("getUnique(Array_RK, iseq = iseq_RK)")

112 call disp%show( getUnique(Array_RK, iseq = iseq_RK) )

113

114 call disp%skip()

115 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

116 call disp%show("! Unique case-insensitive instances within the character array.")

117 call disp%show("!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%")

118 call disp%skip()

119

120 string_SK = "ABBAbbA"

121

122 call disp%show("string_SK")

123 call disp%show( string_SK, deliml = SK_"""" )

124 call disp%show("getUnique(string_SK, iseq = iseq_SK)")

125 call disp%show( getUnique(string_SK, iseq = iseq_SK), deliml = SK_"""" )

126

127contains

128

129 pure function iseq_RK(element1, element2) result(iseq)

130 real(RK) , intent(in) :: element1, element2

131 logical(LK) :: iseq

132 iseq = abs(abs(element1) - abs(element2)) < 0.05_RK

133 end function

134

135 pure function iseq_SK(element1, element2) result(iseq)

136 use pm_strASCII, only: getStrLower

137 character(*, SK) , intent(in) :: element1, element2

138 logical(LK) :: iseq

139 iseq = getStrLower(element1) == getStrLower(element2)

140 end function

141

142end program example

pm_io::show
This is a generic method of the derived type display_type with pass attribute.
Definition: pm_io.F90:11726

pm_io::skip
This is a generic method of the derived type display_type with pass attribute.
Definition: pm_io.F90:11508

pm_strASCII::getStrLower
Generate and return the input string where the uppercase English alphabets are all converted to lower...
Definition: pm_strASCII.F90:4092

pm_io
This module contains classes and procedures for input/output (IO) or generic display operations on st...
Definition: pm_io.F90:252

pm_io::disp
type(display_type) disp
This is a scalar module variable an object of type display_type for general display.
Definition: pm_io.F90:11393

pm_strASCII
This module contains the uncommon and hardly representable ASCII characters as well as procedures for...
Definition: pm_strASCII.F90:61

pm_io::display_type
Generate and return an object of type display_type.
Definition: pm_io.F90:10282

Example Unix compile command via Intel ifort compiler ⛓
1#!/usr/bin/env sh

2rm main.exe

3ifort -fpp -standard-semantics -O3 -Wl,-rpath,../../../lib -I../../../inc main.F90 ../../../lib/libparamonte* -o main.exe

4./main.exe

Example Windows Batch compile command via Intel ifort compiler ⛓
1del main.exe

2set PATH=..\..\..\lib;%PATH%

3ifort /fpp /standard-semantics /O3 /I:..\..\..\include main.F90 ..\..\..\lib\libparamonte*.lib /exe:main.exe

4main.exe

Example Unix / MinGW compile command via GNU gfortran compiler ⛓
1#!/usr/bin/env sh

2rm main.exe

3gfortran -cpp -ffree-line-length-none -O3 -Wl,-rpath,../../../lib -I../../../inc main.F90 ../../../lib/libparamonte* -o main.exe

4./main.exe

Example output ⛓
1

2!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

3!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

4! Find all unique elements in array.

5!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

6!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

7

8

9!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

10! Unique elements in character scalar.

11!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

12

13string_SK

14"ParaMonte is a Monte Carlo Library."

15getUnique(string_SK)

16"ParMonte isClLby."

17

18!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

19! Unique elements in character array.

20!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

21

22Array_SK

23"ParaMonte", "PARAMONTE", "paramonte", "ParaMonte", "ParaMonte", "Paramonte"

24getUnique(Array_SK)

25"ParaMonte", "PARAMONTE", "paramonte", "Paramonte"

26

27!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

28! Unique elements in integer array.

29!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

30

31Array_IK

32+1, +1, +4, +4

33getUnique(Array_IK)

34+1, +4

35

36!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

37! Unique elements in complex array.

38!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

39

40Array_CK

41(+1.0000000000000000, -1.0000000000000000), (+1.0000000000000000, -2.0000000000000000), (+1.0000000000000000, -1.0000000000000000), (+4.0000000000000000, -4.0000000000000000)

42getUnique(Array_CK)

43(+1.0000000000000000, -1.0000000000000000), (+1.0000000000000000, -2.0000000000000000), (+4.0000000000000000, -4.0000000000000000)

44

45!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

46! Unique elements in real array.

47!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

48

49Array_RK

50+1.0000000000000000, +2.0000000000000000, +4.0000000000000000, +4.0000000000000000

51getUnique(Array_RK)

52+1.0000000000000000, +2.0000000000000000, +4.0000000000000000

53

54!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

55!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

56! Find all unique elements according to the user-specified equivalence criterion.

57!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

58!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

59

60

61!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

62! Unique elements in real array.

63!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

64

65Array_RK

66+1.0100000000000000, +1.0400000000000000, +0.97999999999999998, +1.0000000000000000, +1.0200000000000000, +2.0000000000000000

67getUnique(Array_RK, iseq = iseq_RK)

68+1.0100000000000000, +2.0000000000000000

69

70!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

71! Unique case-insensitive instances within the character array.

72!%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

73

74string_SK

75"ABBAbbA"

76getUnique(string_SK, iseq = iseq_SK)

77"AB"

78

Test:: test_pm_arrayUnique

Bug:: Status: Unresolved
Source: Intel Classic Fortran Compiler ifort version 2021.2.0, GNU Fortran Compiler gfortran version 10-11
Description: The Intel Classic Fortran Compiler ifort version 2021.2.0 has a bug for the following interface definition,

character(len(array),SK) , allocatable :: arrayNew(:)

leading to an internal compiler error.

Remedy (as of ParaMonte Library version 2.0.0): For now, the remedy seems to be to redefine the interface as,

character(:, SK), allocatable :: arrayNew(:)

and changing the allocation method accordingly in the implementation to,

allocate(character(len(array, kind = IK)) :: arrayNew(lenArrayNew))

However, this introduces internal compiler error: Segmentation fault with GNU Fortran Compiler gfortran. Here is a code snippet to regenerate the bug in Intel Classic Fortran Compiler ifort (uncomment the commented line to reproduce the gfortran bug),

module pm_explicitLenResult
    implicit none
    interface
        pure module function bug(array) result(arrayNew)
            character(*, SK), intent(in), contiguous    :: array(:)
            character(len(array),SK)    , allocatable   :: arrayNew(:) ! catastrophic internal error with ifort 2021.2. Fine with gfortran 10.3
           !character(:, SK)            , allocatable   :: arrayNew(:) ! catastrophic internal error with gfortran 10.3. Fine with ifort 2021.2
        end function
    end interface
end module pm_explicitLenResult
 
submodule (pm_explicitLenResult) routines
    implicit none
contains
    module procedure bug
       allocate(arrayNew, source = array)
    end procedure
end submodule routines
 
program main
    use pm_explicitLenResult, only: bug
    character(2) :: array(3) = ["AA", "BB", "CC"]
    character(2), allocatable :: arrayNew(:)
    arrayNew = bug(array)
end program main

Remedy (as of ParaMonte Library version 2.0.0): It turns out that both GNU Fortran Compiler gfortran and Intel Classic Fortran Compiler ifort do not tolerate the separation of interface from implementation in the above code snippet.
If one duplicates the interface in the implementation submodule, then both compilers compile and run the code with no errors.
This is the remedy that is currently used in this getRemoved generic interface (interface duplication where the bug exists).
Here is a workaround example for the bug in the above code snippet,

module pm_explicitLenResult
    implicit none
    interface
        pure module function bug(array) result(arrayNew)
            character(*, SK), intent(in), contiguous    :: array(:)
            character(len(array),SK)   , allocatable   :: arrayNew(:) ! catastrophic internal error with ifort 2021.2. Fine with gfortran 10.3
        end function
    end interface
end module pm_explicitLenResult
 
submodule (pm_explicitLenResult) routines
    implicit none
contains
    module procedure bug
       allocate(arrayNew, source = array)
    end procedure
end submodule routines
 
program main
    use pm_explicitLenResult, only: bug
    character(2) :: array(3) = ["AA", "BB", "CC"]
    character(2), allocatable :: arrayNew(:)
    arrayNew = bug(array)
end program main

Todo:: Low Priority: This generic interface can be extended to 2D input objects.

Todo:: Critical Priority: The internal compiler error with ifort and gfortran has to be fixed in the future versions.

Final Remarks ⛓

If you believe this algorithm or its documentation can be improved, we appreciate your contribution and help to edit this page's documentation and source file on GitHub.
For details on the naming abbreviations, see this page.
For details on the naming conventions, see this page.
This software is distributed under the MIT license with additional terms outlined below.

If you use any parts or concepts from this library to any extent, please acknowledge the usage by citing the relevant publications of the ParaMonte library.
If you regenerate any parts/ideas from this library in a programming environment other than those currently supported by this ParaMonte library (i.e., other than C, C++, Fortran, MATLAB, Python, R), please also ask the end users to cite this original ParaMonte library.

This software is available to the public under a highly permissive license.
Help us justify its continued development and maintenance by acknowledging its benefit to society, distributing it, and contributing to it.

Copyright: Computational Data Science Lab

Author:: Amir Shahmoradi, September 1, 2017, 11:35 PM, Institute for Computational Engineering and Sciences (ICES), The University of Texas at Austin

Definition at line 2682 of file pm_arrayUnique.F90.

The documentation for this interface was generated from the following file:

src/fortran/main/pm_arrayUnique.F90