Terse Method to Swap Lowest for Highest?Efficient method for Inserting arrays into arraysSwap elements in list without copyBetter method to swap the values of two 2-D arraysHow to get this list with a terse methodBuilt-in (or Terse) Method to Combine and Transpose DatasetsAre there more readable and terse method can get this listefficiently method for generating a sequenceSimple method to sort versionsFunction for SortBySwap Elements of a continuous List, possible?
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Terse Method to Swap Lowest for Highest?
Efficient method for Inserting arrays into arraysSwap elements in list without copyBetter method to swap the values of two 2-D arraysHow to get this list with a terse methodBuilt-in (or Terse) Method to Combine and Transpose DatasetsAre there more readable and terse method can get this listefficiently method for generating a sequenceSimple method to sort versionsFunction for SortBySwap Elements of a continuous List, possible?
$begingroup$
I have built a solution to swap the lowest values with the highest values in a list.
With
SeedRandom[987]
test = RandomSample@*Join @@ Range @@@ 6, 10, 56, 60, 1, 5, -5, -1
-1, 2, 7, 8, 60, 57, 58, 10, 9, 4, -5, -3, 3, 59, 1, 5, -4, 6, -2, 56
Then
swapPositions =
PermutationReplace[
Ordering@Ordering@test,
With[len = Length@test,
Cycles@
Transpose@Range @@ 1, Floor[len/2], Reverse@*Range @@ Ceiling[len/2] + 1, len
]
];
Sort[test][[swapPositions]]
56, 9, 4, 3, -5, -2, -3, 1, 2, 7, 60, 58, 8, -4, 10, 6, 59, 5, 57, -1
The largest half of the numbers have had their positions swapped with lowest half of the numbers.
However, it feels too verbose and I think Sort
might be expensive in this case. Is there a built-in function or more terse method to achieve this. Of course with no loss in speed. The actual case is for list of length 100000 and more.
list-manipulation performance-tuning sorting
$endgroup$
add a comment |
$begingroup$
I have built a solution to swap the lowest values with the highest values in a list.
With
SeedRandom[987]
test = RandomSample@*Join @@ Range @@@ 6, 10, 56, 60, 1, 5, -5, -1
-1, 2, 7, 8, 60, 57, 58, 10, 9, 4, -5, -3, 3, 59, 1, 5, -4, 6, -2, 56
Then
swapPositions =
PermutationReplace[
Ordering@Ordering@test,
With[len = Length@test,
Cycles@
Transpose@Range @@ 1, Floor[len/2], Reverse@*Range @@ Ceiling[len/2] + 1, len
]
];
Sort[test][[swapPositions]]
56, 9, 4, 3, -5, -2, -3, 1, 2, 7, 60, 58, 8, -4, 10, 6, 59, 5, 57, -1
The largest half of the numbers have had their positions swapped with lowest half of the numbers.
However, it feels too verbose and I think Sort
might be expensive in this case. Is there a built-in function or more terse method to achieve this. Of course with no loss in speed. The actual case is for list of length 100000 and more.
list-manipulation performance-tuning sorting
$endgroup$
add a comment |
$begingroup$
I have built a solution to swap the lowest values with the highest values in a list.
With
SeedRandom[987]
test = RandomSample@*Join @@ Range @@@ 6, 10, 56, 60, 1, 5, -5, -1
-1, 2, 7, 8, 60, 57, 58, 10, 9, 4, -5, -3, 3, 59, 1, 5, -4, 6, -2, 56
Then
swapPositions =
PermutationReplace[
Ordering@Ordering@test,
With[len = Length@test,
Cycles@
Transpose@Range @@ 1, Floor[len/2], Reverse@*Range @@ Ceiling[len/2] + 1, len
]
];
Sort[test][[swapPositions]]
56, 9, 4, 3, -5, -2, -3, 1, 2, 7, 60, 58, 8, -4, 10, 6, 59, 5, 57, -1
The largest half of the numbers have had their positions swapped with lowest half of the numbers.
However, it feels too verbose and I think Sort
might be expensive in this case. Is there a built-in function or more terse method to achieve this. Of course with no loss in speed. The actual case is for list of length 100000 and more.
list-manipulation performance-tuning sorting
$endgroup$
I have built a solution to swap the lowest values with the highest values in a list.
With
SeedRandom[987]
test = RandomSample@*Join @@ Range @@@ 6, 10, 56, 60, 1, 5, -5, -1
-1, 2, 7, 8, 60, 57, 58, 10, 9, 4, -5, -3, 3, 59, 1, 5, -4, 6, -2, 56
Then
swapPositions =
PermutationReplace[
Ordering@Ordering@test,
With[len = Length@test,
Cycles@
Transpose@Range @@ 1, Floor[len/2], Reverse@*Range @@ Ceiling[len/2] + 1, len
]
];
Sort[test][[swapPositions]]
56, 9, 4, 3, -5, -2, -3, 1, 2, 7, 60, 58, 8, -4, 10, 6, 59, 5, 57, -1
The largest half of the numbers have had their positions swapped with lowest half of the numbers.
However, it feels too verbose and I think Sort
might be expensive in this case. Is there a built-in function or more terse method to achieve this. Of course with no loss in speed. The actual case is for list of length 100000 and more.
list-manipulation performance-tuning sorting
list-manipulation performance-tuning sorting
edited 32 mins ago
m_goldberg
87.7k872198
87.7k872198
asked 1 hour ago
EdmundEdmund
26.6k330102
26.6k330102
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
How about:
Module[tmp = test,
With[ord=Ordering[tmp],
tmp[[ord]] = Reverse @ tmp[[ord]]];
tmp
]
56, 9, 4, 3, -5, -2, -3, 1, 2, 7, 60, 58, 8, -4, 10, 6, 59, 5, 57, -1
$endgroup$
$begingroup$
That is so obvious I want to cry. Thanks (+1).
$endgroup$
– Edmund
50 mins ago
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
How about:
Module[tmp = test,
With[ord=Ordering[tmp],
tmp[[ord]] = Reverse @ tmp[[ord]]];
tmp
]
56, 9, 4, 3, -5, -2, -3, 1, 2, 7, 60, 58, 8, -4, 10, 6, 59, 5, 57, -1
$endgroup$
$begingroup$
That is so obvious I want to cry. Thanks (+1).
$endgroup$
– Edmund
50 mins ago
add a comment |
$begingroup$
How about:
Module[tmp = test,
With[ord=Ordering[tmp],
tmp[[ord]] = Reverse @ tmp[[ord]]];
tmp
]
56, 9, 4, 3, -5, -2, -3, 1, 2, 7, 60, 58, 8, -4, 10, 6, 59, 5, 57, -1
$endgroup$
$begingroup$
That is so obvious I want to cry. Thanks (+1).
$endgroup$
– Edmund
50 mins ago
add a comment |
$begingroup$
How about:
Module[tmp = test,
With[ord=Ordering[tmp],
tmp[[ord]] = Reverse @ tmp[[ord]]];
tmp
]
56, 9, 4, 3, -5, -2, -3, 1, 2, 7, 60, 58, 8, -4, 10, 6, 59, 5, 57, -1
$endgroup$
How about:
Module[tmp = test,
With[ord=Ordering[tmp],
tmp[[ord]] = Reverse @ tmp[[ord]]];
tmp
]
56, 9, 4, 3, -5, -2, -3, 1, 2, 7, 60, 58, 8, -4, 10, 6, 59, 5, 57, -1
answered 55 mins ago
Carl WollCarl Woll
71.2k394185
71.2k394185
$begingroup$
That is so obvious I want to cry. Thanks (+1).
$endgroup$
– Edmund
50 mins ago
add a comment |
$begingroup$
That is so obvious I want to cry. Thanks (+1).
$endgroup$
– Edmund
50 mins ago
$begingroup$
That is so obvious I want to cry. Thanks (+1).
$endgroup$
– Edmund
50 mins ago
$begingroup$
That is so obvious I want to cry. Thanks (+1).
$endgroup$
– Edmund
50 mins ago
add a comment |
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