Assignment (Selective) (EXP X)←Y

X is the name of a variable in the workspace, possibly modified by the indexing function (EXP X[I])←Y, see Assignment (Indexed). EXP is an expression that selects elements of X. Y is an array expression. The result of the expression Y is allocated to the elements of X selected by EXP. Note that X may refer to a single name only.

The following functions may appear in the selection expression. Where appropriate these functions may be used with axis [] and with the Each operator ¨.

Table 1: Functions for Selective Assignment
`↑`	Take
`↓`	Drop
`,`	Ravel
`⍪`	Table
`⌽⊖`	Reverse, Rotate
`⍴`	Reshape
`⊃`	Disclose, Pick
`⍉`	Transpose (Monadic and Dyadic)
`/⌿`	Replicate
`\⍀`	Expand
`⌷`	Index
`∊`	Enlist ( `⎕ML≥1` )

Note: Mix and Split (monadic ↑ and ↓), Type (monadic ∊ when ⎕ML<1) and Membership (dyadic ∊) may not be used in the selection expression.

Examples

      A←'HELLO'
      ((A∊'AEIOU')/A)←'*'

      A
H*LL*

      Z←3 4⍴⍳12
      (5↑,Z)←0

      Z
0  0  0  0
0  6  7  8
9 10 11 12

      MAT←3 3⍴⍳9
      (1 1⍉MAT)←0

      MAT
0 2 3
4 0 6
7 8 0

      ⎕ML←1⍝ so ∊ is Enlist
      names←'Andy' 'Karen' 'Liam'
      (('a'=∊names)/∊names)←'*'
      names
 Andy  K*ren  Li*m

Each Operator

The functions listed in the table above may also be used with the Each Operator ¨.

Examples

      A←'HELLO' 'WORLD'
      (2↑¨A)←'*'
      A
 **LLO  **RLD

      A←'HELLO' 'WORLD'
      ((A='O')/¨A)←'*'
      A
 HELL*  W*RLD

      A←'HELLO' 'WORLD'
      ((A∊¨⊂'LO')/¨A)←'*'
      A
 HE***  W*R*D

Bracket Indexing

Bracket indexing may also be applied to the expression on the left of the assignment arrow.

Examples

      MAT←4 3⍴'Hello' 'World'
      (¯2↑¨MAT[;1 3])←'$'
      MAT
 Hel$$  World  Hel$$ 
 Wor$$  Hello  Wor$$ 
 Hel$$  World  Hel$$ 
 Wor$$  Hello  Wor$$