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-- Status: rewritten July 2018
-- Author: Lily Silverstein
doc ///
Key
take
(take, BasicList, ZZ)
(take, BasicList, List)
(take, Thing, ZZ)
(take, Thing, List)
Headline
Take some elements from a list or sequence.
Usage
take(L, i)
take(L, {j,k})
take(x, i)
Inputs
L: BasicList
x: Thing
i: ZZ
j: ZZ
k: ZZ
Outputs
L2: BasicList
the list or sequence containing the first {\tt i} elements of {\tt L},
(if {\tt i} positive), or the last {\tt i} elements of {\tt L} (if {\tt i} negative), or, if given the
pair {\tt j,k}, the list or sequence containing the elements of {\tt L} with indices {\tt j} through {\tt k}
Description
Example
take({a,b,c,d,e,f,g}, 3)
take({a,b,c,d,e,f,g}, -3)
take({a,b,c,d,e,f,g}, {1,3})
take({a,b,c,d,e,f,g}, {2,2})
Text
The pair $\{j,k\}$ must be given with both entries non-negative, and $j\le k$. Otherwise an empty list is returned.
Example
take({a,b,c,d,e,f,g}, {3,1})
take({a,b,c,d,e,f,g}, {4,-1})
Text
If @TT "x"@ is any object belonging to a class with the @TO iterator@ method
installed, then a list containing the first $i$ (or the $(j+1)$th
through $(k+1)$th) objects returned when @TO next@ is called on the output
of @M2CODE "iterator x"@ is returned. If fewer than $i$ (or $k+1$) objects
are returned before the @TO StopIteration@ symbol is encountered, then the
list will have shorter than expected length.
Example
take("Hello, world!", 5)
take("Hello, world!", 20)
take("Hello, world!", {7, 11})
SeeAlso
drop
select
position
positions
"lists and sequences"
///
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