> For the complete documentation index, see [llms.txt](https://docs.urbit.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.urbit.org/hoon/lagoon/structure.md).
# Structures
### `+reshape`
Reshape an array into an array with the same total number of elements.
**Accepts**
Parameters as specified in source
**Produces**
A `$ray`.
**Source**
```hoon
++ reshape
|= [a=ray shape=(list @)]
^- ray
?> (check a)
=/ in-cnt (reel shape.meta.a ^mul)
=/ out-cnt (reel shape ^mul)
?> =(in-cnt out-cnt)
=. shape.meta.a shape
a
```
***
### `+stack`
Stack along dimension (0 row, 1 col, 2 lay, etc.).
**Accepts**
Parameters as specified in source
**Produces**
A `$ray`.
**Source**
```hoon
++ stack
~/ %stack
|= [a=ray b=ray dim=@ud]
^- ray
?> (check a)
?> (check b)
:: check same dims overall
?> =((lent shape.meta.a) (lent shape.meta.b))
:: check same dims other than target dim
?> =/ idx 0
|- ^- ?
?: =(idx (lent shape.meta.a)) %.y
?: =(dim idx) $(idx +(idx))
?. =((snag idx shape.meta.a) (snag idx shape.meta.b))
%.n
$(idx +(idx))
?> (^lte dim (lent shape.meta.a))
=| c=ray
?: =(0 dim)
=. meta.c meta.a
=. shape.meta.c
:- (^add (snag dim shape.meta.a) (snag dim shape.meta.b))
+.shape.meta.a
=. data.c (con (lsh [bloq.meta.a (roll shape.meta.a ^mul)] data.a) data:(unspac b))
c
?: =(1 dim)
=. meta.c meta.a
=. shape.meta.c
(snap shape.meta.c dim (^add (snag dim shape.meta.a) (snag dim shape.meta.b)))
=/ c (zeros meta.c)
=/ idx 0
|- ^- ray
?: =((snag 0 (flop shape.meta.a)) idx) c
=/ off (weld (snip (snip shape.meta.a)) ~[idx])
=/ row-a (get-row a off)
=/ row-b (get-row b off)
=/ data-c (con (lsh [bloq.meta.a (snag 1 shape.meta.row-a)] data.row-a) data:(unspac row-b))
=/ meta-c=meta meta.row-a
=. shape.meta-c (snap shape.meta-c dim (^add (snag dim shape.meta.row-a) (snag dim shape.meta.row-b)))
=/ row-c=ray (spac [meta-c data-c])
%= $
idx +(idx)
c (set-row c off row-c)
==
!!
```
***
### `+hstack`
Horizontally stack two arrays.
**Accepts**
Parameters as specified in source
**Produces**
A `$ray`.
**Source**
```hoon
++ hstack
|= [a=ray b=ray]
^- ray
(stack a b 1)
```
***
### `+vstack`
Vertically stack two arrays.
**Accepts**
Parameters as specified in source
**Produces**
A `$ray`.
**Source**
```hoon
++ vstack
|= [a=ray b=ray]
^- ray
(stack a b 0)
```
***
### `+transpose`
Transpose a 2D array.
**Accepts**
A `$ray`.
**Produces**
A `$ray`.
**Source**
```hoon
++ transpose
~/ %transpose
|= a=ray ^- ray
?> (check a)
=, meta.a
?> =(2 (lent shape))
=/ i 0
=/ j 0
=/ shape=(list @) ~[(snag 1 shape) (snag 0 shape)]
=/ prod=ray (zeros [shape bloq kind ~])
|-
?: =(i (snag 0 shape.meta.a))
prod
%= $
i +(i)
prod
|-
?: =(j (snag 1 shape.meta.a))
prod
%= $
j +(j)
prod (set-item prod ~[j i] (get-item a ~[i j]))
==
==
```
---
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