Re: fast way of appending x zeros to a list?
- To: mathgroup at smc.vnet.net
- Subject: [mg79147] Re: [mg79090] fast way of appending x zeros to a list?
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Thu, 19 Jul 2007 03:42:25 -0400 (EDT)
- Reply-to: hanlonr at cox.net
data = Table[RandomInteger[5], {RandomInteger[{5, 10}]}]
{5,0,0,5,3,1,3,4}
numberOfZeroes = 5;
Join[Table[0, {numberOfZeroes}], data]
{0,0,0,0,0,5,0,0,5,3,1,3,4}
% == PadLeft[data, Length[data] + numberOfZeroes]
True
Bob Hanlon
---- kristoph <kristophs.post at web.de> wrote:
> Dear all,
>
> I'm looking for a fast way to append 0's to a list. Unfortunately, I
> append a variable number of 0's to a list which is generated by a
> For[...]-loop. Therefore, PadLeft[...] is not variable enough to
> append exactly x zeros to the list.
>
> At the moment I use: Do[PrependTo[data,0],{K}] where the K depends on
> certain factors.
>
> In case you have an idea to append exactly x zeros to the left quickly
> I would be more that happy since I heard that the PrependTo[...] and
> AppendTo[...] functions are very slow.
>
> Thanks a lot.
>
>
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