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How to transpose the 1st and -1th levels of arbitrarily nested array?
The Next CEO of Stack OverflowEmulating R data frame getters with UpValuesQuickly pruning elements in one structured array that exist in a separate unordered arrayJoining sub-lists nested two levels deep in a list`Part` like `Delete`: How to delete list of columns or arbitrarily deeper levelsHow to mesh a region using adaptive cubic elementsHow to efficiently Flatten nested lists while preserving select levels?Distribute elements of one line across arbitrary dimension of another listDeep level nested list addition`Transpose` nested `Association`Reformatting the pattern inside a list
$begingroup$
Is there a straightforward way to convert
arr =
a, b, a, b, a, b, a, b, a, b, a, b, a, b, a, b
;
to:
a, a, a, a, a, a, a, a, b, b, b, b, b, b, b, b
?
So I need to swap the first and last dimension. Which should in principle be possible because altough arr does not have a fixed structure the 'bottom' is always uniform:
Level[arr, -2]
a, b, a, b, a, b, a, b, a, b, a, b, a, b, a, b
Had Transpose/Flatten/MapThread accepted negative level specification it would have been easy. That is not the case.
One can think about that question as: how to create arr2 so that arr[[whatever__, y_]] == arr2[[y, whatever__]].
EDIT:
In general Level[arr, -2] should be a rectangular array but rows do not need to be the same.
list-manipulation
asked 1 hour ago
Kuba♦Kuba
107k12210531
$endgroup$
add a comment |
$begingroup$
Is there a straightforward way to convert
arr =
a, b, a, b, a, b, a, b, a, b, a, b, a, b, a, b
;
to:
a, a, a, a, a, a, a, a, b, b, b, b, b, b, b, b
?
So I need to swap the first and last dimension. Which should in principle be possible because altough arr does not have a fixed structure the 'bottom' is always uniform:
Level[arr, -2]
a, b, a, b, a, b, a, b, a, b, a, b, a, b, a, b
Had Transpose/Flatten/MapThread accepted negative level specification it would have been easy. That is not the case.
One can think about that question as: how to create arr2 so that arr[[whatever__, y_]] == arr2[[y, whatever__]].
EDIT:
In general Level[arr, -2] should be a rectangular array but rows do not need to be the same.
list-manipulation
asked 1 hour ago
Kuba♦Kuba
107k12210531
$endgroup$
$begingroup$
Not a solution, butFlatten[MapIndexed[RotateRight[#2] -> #1 &, arr, -1]]gives you a list of rules of what needs to be constructed. I don't know of a way to construct it though:SparseArraydoes not construct ragged structures.
$endgroup$
– Roman
1 hour ago
$begingroup$
Maybe something along the lines ofarr /. a,b->a,a,b->b? Or perhaps more generally,arr /. a_?VectorQ :> First@a, a_?VectorQ :> Last@a?
$endgroup$
– Carl Woll
1 hour ago
$begingroup$
Does your list always containa,bat the lowest level, or can there be anything there as long as they're all of same length?
$endgroup$
– Roman
1 hour ago
$begingroup$
@Roman Level[arr, -2]` should be a rectangular array but rows do not need to be the same.
$endgroup$
– Kuba♦
59 mins ago
$begingroup$
@Kuba maybe you can come up with a recursion that constructs the result from the list of rules I gave 4 lines up? That would be a handy tool to have in any case.
$endgroup$
– Roman
57 mins ago
add a comment |
$begingroup$
Is there a straightforward way to convert
arr =
a, b, a, b, a, b, a, b, a, b, a, b, a, b, a, b
;
to:
a, a, a, a, a, a, a, a, b, b, b, b, b, b, b, b
?
So I need to swap the first and last dimension. Which should in principle be possible because altough arr does not have a fixed structure the 'bottom' is always uniform:
Level[arr, -2]
a, b, a, b, a, b, a, b, a, b, a, b, a, b, a, b
Had Transpose/Flatten/MapThread accepted negative level specification it would have been easy. That is not the case.
One can think about that question as: how to create arr2 so that arr[[whatever__, y_]] == arr2[[y, whatever__]].
EDIT:
In general Level[arr, -2] should be a rectangular array but rows do not need to be the same.
list-manipulation
asked 1 hour ago
Kuba♦Kuba
107k12210531
$endgroup$
Is there a straightforward way to convert
arr =
a, b, a, b, a, b, a, b, a, b, a, b, a, b, a, b
;
to:
a, a, a, a, a, a, a, a, b, b, b, b, b, b, b, b
?
So I need to swap the first and last dimension. Which should in principle be possible because altough arr does not have a fixed structure the 'bottom' is always uniform:
Level[arr, -2]
a, b, a, b, a, b, a, b, a, b, a, b, a, b, a, b
Had Transpose/Flatten/MapThread accepted negative level specification it would have been easy. That is not the case.
One can think about that question as: how to create arr2 so that arr[[whatever__, y_]] == arr2[[y, whatever__]].
EDIT:
In general Level[arr, -2] should be a rectangular array but rows do not need to be the same.
list-manipulation
list-manipulation
asked 1 hour ago
Kuba♦Kuba
107k12210531
asked 1 hour ago
Kuba♦Kuba
107k12210531
edited 58 mins ago
Kuba
asked 1 hour ago
Kuba♦Kuba
107k12210531
asked 1 hour ago
Kuba♦Kuba
107k12210531
asked 1 hour ago
Kuba♦Kuba
107k12210531
107k12210531
$begingroup$
Not a solution, butFlatten[MapIndexed[RotateRight[#2] -> #1 &, arr, -1]]gives you a list of rules of what needs to be constructed. I don't know of a way to construct it though:SparseArraydoes not construct ragged structures.
$endgroup$
– Roman
1 hour ago
$begingroup$
Maybe something along the lines ofarr /. a,b->a,a,b->b? Or perhaps more generally,arr /. a_?VectorQ :> First@a, a_?VectorQ :> Last@a?
$endgroup$
– Carl Woll
1 hour ago
$begingroup$
Does your list always containa,bat the lowest level, or can there be anything there as long as they're all of same length?
$endgroup$
– Roman
1 hour ago
$begingroup$
@Roman Level[arr, -2]` should be a rectangular array but rows do not need to be the same.
$endgroup$
– Kuba♦
59 mins ago
$begingroup$
@Kuba maybe you can come up with a recursion that constructs the result from the list of rules I gave 4 lines up? That would be a handy tool to have in any case.
$endgroup$
– Roman
57 mins ago
add a comment |
$begingroup$
Not a solution, butFlatten[MapIndexed[RotateRight[#2] -> #1 &, arr, -1]]gives you a list of rules of what needs to be constructed. I don't know of a way to construct it though:SparseArraydoes not construct ragged structures.
$endgroup$
– Roman
1 hour ago
$begingroup$
Maybe something along the lines ofarr /. a,b->a,a,b->b? Or perhaps more generally,arr /. a_?VectorQ :> First@a, a_?VectorQ :> Last@a?
$endgroup$
– Carl Woll
1 hour ago
$begingroup$
Does your list always containa,bat the lowest level, or can there be anything there as long as they're all of same length?
$endgroup$
– Roman
1 hour ago
$begingroup$
@Roman Level[arr, -2]` should be a rectangular array but rows do not need to be the same.
$endgroup$
– Kuba♦
59 mins ago
$begingroup$
@Kuba maybe you can come up with a recursion that constructs the result from the list of rules I gave 4 lines up? That would be a handy tool to have in any case.
$endgroup$
– Roman
57 mins ago
$begingroup$
Not a solution, but
Flatten[MapIndexed[RotateRight[#2] -> #1 &, arr, -1]] gives you a list of rules of what needs to be constructed. I don't know of a way to construct it though: SparseArray does not construct ragged structures.$endgroup$
– Roman
1 hour ago
$begingroup$
Not a solution, but
Flatten[MapIndexed[RotateRight[#2] -> #1 &, arr, -1]] gives you a list of rules of what needs to be constructed. I don't know of a way to construct it though: SparseArray does not construct ragged structures.$endgroup$
– Roman
1 hour ago
$begingroup$
Maybe something along the lines of
arr /. a,b->a,a,b->b? Or perhaps more generally, arr /. a_?VectorQ :> First@a, a_?VectorQ :> Last@a?$endgroup$
– Carl Woll
1 hour ago
$begingroup$
Maybe something along the lines of
arr /. a,b->a,a,b->b? Or perhaps more generally, arr /. a_?VectorQ :> First@a, a_?VectorQ :> Last@a?$endgroup$
– Carl Woll
1 hour ago
$begingroup$
Does your list always contain
a,b at the lowest level, or can there be anything there as long as they're all of same length?$endgroup$
– Roman
1 hour ago
$begingroup$
Does your list always contain
a,b at the lowest level, or can there be anything there as long as they're all of same length?$endgroup$
– Roman
1 hour ago
$begingroup$
@Roman Level[arr, -2]` should be a rectangular array but rows do not need to be the same.
$endgroup$
– Kuba♦
59 mins ago
$begingroup$
@Roman Level[arr, -2]` should be a rectangular array but rows do not need to be the same.
$endgroup$
– Kuba♦
59 mins ago
$begingroup$
@Kuba maybe you can come up with a recursion that constructs the result from the list of rules I gave 4 lines up? That would be a handy tool to have in any case.
$endgroup$
– Roman
57 mins ago
$begingroup$
@Kuba maybe you can come up with a recursion that constructs the result from the list of rules I gave 4 lines up? That would be a handy tool to have in any case.
$endgroup$
– Roman
57 mins ago
add a comment |
3 Answers
3
active
oldest
votes
$begingroup$
arr = a, b, a, b, a, b, a, b, a, b, a, b, a, b, a, b;
SetAttributes[f1, Listable]
Apply[f1, arr, 0, -3] /. f1 -> List
a, a, a, a, a, a, a, a, b, b, b, b, b, b, b, b
answered 56 mins ago
andre314andre314
12.2k12352
$endgroup$
add a comment |
$begingroup$
This is what the list at the lowest level looks like:
el = First@Level[list, -2];
Using this, we can solve it with a rules-based approach:
list /. el -> # & /@ el
or a recursive approach like this:
walk[lists : __List, i_] := walk[#, i] & /@ lists
walk[atoms : __, i_] := i
walk[list, #] & /@ el
answered 1 hour ago
C. E.C. E.
50.8k399205
$endgroup$
add a comment |
$begingroup$
Terrible solution using Table but works:
Table[Map[#[[i]] &, arr, -2], i, Last[Dimensions[Level[arr, -2]]]]
answered 33 mins ago
RomanRoman
3,9361022
$endgroup$
add a comment |
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
arr = a, b, a, b, a, b, a, b, a, b, a, b, a, b, a, b;
SetAttributes[f1, Listable]
Apply[f1, arr, 0, -3] /. f1 -> List
a, a, a, a, a, a, a, a, b, b, b, b, b, b, b, b
answered 56 mins ago
andre314andre314
12.2k12352
$endgroup$
add a comment |
$begingroup$
arr = a, b, a, b, a, b, a, b, a, b, a, b, a, b, a, b;
SetAttributes[f1, Listable]
Apply[f1, arr, 0, -3] /. f1 -> List
a, a, a, a, a, a, a, a, b, b, b, b, b, b, b, b
answered 56 mins ago
andre314andre314
12.2k12352
$endgroup$
add a comment |
$begingroup$
arr = a, b, a, b, a, b, a, b, a, b, a, b, a, b, a, b;
SetAttributes[f1, Listable]
Apply[f1, arr, 0, -3] /. f1 -> List
a, a, a, a, a, a, a, a, b, b, b, b, b, b, b, b
answered 56 mins ago
andre314andre314
12.2k12352
$endgroup$
arr = a, b, a, b, a, b, a, b, a, b, a, b, a, b, a, b;
SetAttributes[f1, Listable]
Apply[f1, arr, 0, -3] /. f1 -> List
a, a, a, a, a, a, a, a, b, b, b, b, b, b, b, b
answered 56 mins ago
andre314andre314
12.2k12352
answered 56 mins ago
andre314andre314
12.2k12352
answered 56 mins ago
andre314andre314
12.2k12352
answered 56 mins ago
andre314andre314
12.2k12352
12.2k12352
add a comment |
add a comment |
$begingroup$
This is what the list at the lowest level looks like:
el = First@Level[list, -2];
Using this, we can solve it with a rules-based approach:
list /. el -> # & /@ el
or a recursive approach like this:
walk[lists : __List, i_] := walk[#, i] & /@ lists
walk[atoms : __, i_] := i
walk[list, #] & /@ el
answered 1 hour ago
C. E.C. E.
50.8k399205
$endgroup$
add a comment |
$begingroup$
This is what the list at the lowest level looks like:
el = First@Level[list, -2];
Using this, we can solve it with a rules-based approach:
list /. el -> # & /@ el
or a recursive approach like this:
walk[lists : __List, i_] := walk[#, i] & /@ lists
walk[atoms : __, i_] := i
walk[list, #] & /@ el
answered 1 hour ago
C. E.C. E.
50.8k399205
$endgroup$
add a comment |
$begingroup$
This is what the list at the lowest level looks like:
el = First@Level[list, -2];
Using this, we can solve it with a rules-based approach:
list /. el -> # & /@ el
or a recursive approach like this:
walk[lists : __List, i_] := walk[#, i] & /@ lists
walk[atoms : __, i_] := i
walk[list, #] & /@ el
answered 1 hour ago
C. E.C. E.
50.8k399205
$endgroup$
This is what the list at the lowest level looks like:
el = First@Level[list, -2];
Using this, we can solve it with a rules-based approach:
list /. el -> # & /@ el
or a recursive approach like this:
walk[lists : __List, i_] := walk[#, i] & /@ lists
walk[atoms : __, i_] := i
walk[list, #] & /@ el
answered 1 hour ago
C. E.C. E.
50.8k399205
answered 1 hour ago
C. E.C. E.
50.8k399205
answered 1 hour ago
C. E.C. E.
50.8k399205
answered 1 hour ago
C. E.C. E.
50.8k399205
50.8k399205
add a comment |
add a comment |
$begingroup$
Terrible solution using Table but works:
Table[Map[#[[i]] &, arr, -2], i, Last[Dimensions[Level[arr, -2]]]]
answered 33 mins ago
RomanRoman
3,9361022
$endgroup$
add a comment |
$begingroup$
Terrible solution using Table but works:
Table[Map[#[[i]] &, arr, -2], i, Last[Dimensions[Level[arr, -2]]]]
answered 33 mins ago
RomanRoman
3,9361022
$endgroup$
add a comment |
$begingroup$
Terrible solution using Table but works:
Table[Map[#[[i]] &, arr, -2], i, Last[Dimensions[Level[arr, -2]]]]
answered 33 mins ago
RomanRoman
3,9361022
$endgroup$
Terrible solution using Table but works:
Table[Map[#[[i]] &, arr, -2], i, Last[Dimensions[Level[arr, -2]]]]
answered 33 mins ago
RomanRoman
3,9361022
answered 33 mins ago
RomanRoman
3,9361022
answered 33 mins ago
RomanRoman
3,9361022
answered 33 mins ago
RomanRoman
3,9361022
3,9361022
add a comment |
add a comment |
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$begingroup$
Not a solution, but
Flatten[MapIndexed[RotateRight[#2] -> #1 &, arr, -1]]gives you a list of rules of what needs to be constructed. I don't know of a way to construct it though:SparseArraydoes not construct ragged structures.$endgroup$
– Roman
1 hour ago
$begingroup$
Maybe something along the lines of
arr /. a,b->a,a,b->b? Or perhaps more generally,arr /. a_?VectorQ :> First@a, a_?VectorQ :> Last@a?$endgroup$
– Carl Woll
1 hour ago
$begingroup$
Does your list always contain
a,bat the lowest level, or can there be anything there as long as they're all of same length?$endgroup$
– Roman
1 hour ago
$begingroup$
@Roman Level[arr, -2]` should be a rectangular array but rows do not need to be the same.
$endgroup$
– Kuba♦
59 mins ago
$begingroup$
@Kuba maybe you can come up with a recursion that constructs the result from the list of rules I gave 4 lines up? That would be a handy tool to have in any case.
$endgroup$
– Roman
57 mins ago