# Symbol Take

From NARS2000

Revision as of 22:25, 13 February 2016 by Robert Wallick (talk | contribs) (Added examples, expanded)

# ↑ — Take symbol — Keystroke(usually) ALT+y ; Character (⎕UCS) 8593

## Usage

**Dyadic function A↑B** - where **A** is the number of elements to take and **B** is the vector or array to operate on.
Take first(A is positive) n or last(A is negative) n elements of an array.
**Take** and **Rho** share a similar property - the left argument specifies the **size** of the resultant array.

## Examples

5↑1 ⍝Take the first 5 elements, given scalar integer 1 1 0 0 0 0 ⍝Result creates a vector of 5 elements, since only a single scalar was present, 4 additional zeroes are appended to the vector. ¯4↑45 78 33 99 10 11 12 13 ⍝Take the last 4 elements, given a vector of 8 integers 10 11 12 13 ⍝APL/NARS Interpreter returns the last 4 elements, a vector. ¯5↑'abcdefghijklmnop' lmnop ⍝Result is the last 5 elements from the alphabet sub-string(take's right argument), result is similarly a string. A←3 4⍴⍳12 ⍝Store a 3-row by 4-column matrix of the set of integers from 1 through 12 in variable A A ⍝Display the contents of variable A, which has 3 rows and 4 columns of consecutive integers: 1 2 3 4 5 6 7 8 9 10 11 12 2 3↑A ⍝Take just the FIRST 2 rows and 3 columns of variable A, display the requested results: 1 2 3 5 6 7 ¯2 3↑A ⍝Take the LAST 2 rows and FIRST 3 columns of variable A, display the results: 5 6 7 9 10 11 4 5↑A ⍝Take 4 rows and 5 columns of variable A, ZEROES are APPENDED when left arguments exceed array sizes of a NUMERIC matrix. 1 2 3 4 0 5 6 7 8 0 9 10 11 12 0 0 0 0 0 0 ¯4 ¯5↑A ⍝Take negative 4 rows and negative 5 cols of variable A. Result: ZEROES are PREFIXED onto numeric matrix A: 0 0 0 0 0 0 1 2 3 4 0 5 6 7 8 0 9 10 11 12

## See Also

- Rho:
**⍴**especially**Dyadic rho**and it's leftmost argument

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