Re: List Manipulation
- To: mathgroup@smc.vnet.net
- Subject: [mg10497] Re: [mg10471] List Manipulation
- From: "Vittorio G. Caffa" <caffa@iabg.de>" <caffa@iabgmh.iabg.de>"
- Date: Tue, 20 Jan 1998 02:22:46 -0500
- Organization: IABG
Paul Hanson wrote
(1)
> Hola!
> So, if you have a couple of lists:
> {{1},{2},{3},{4}....{n}}
> and
> {{1a},....{na}}
> and I want to combine them such that,
> {{1},{1a},{2},{2a}....{n},{na}}
>
> How do I get there? Thanks in advance for the help.
and (2)
> Hola!
> Hope you're all doing well. If I have a list of n lists, and want to
> get rid of all the even ones how would I go about doing this? That
> is, {{n1},{n2},.....{2n}} converted to {{n1},{n3}...{2n-1}}. I tried
> using the various procedures in Wolfram's book, but nothing seems to
> work (ie, Delete, Take, etc.). Thanks for the help.
Part 1:
In[1]:= aa=Array[a,7]
Out[1]= {a[1],a[2],a[3],a[4],a[5],a[6],a[7]}
In[2]:= bb=Array[b,7]
Out[2]= {b[1],b[2],b[3],b[4],b[5],b[6],b[7]}
In[3]:= cc=Flatten[Transpose[{aa,bb}]]
Out[3]= {a[1],b[1],a[2],b[2],a[3],b[3],a[4],b[4],a[5],b[5],
a[6],b[6],a[7],b[7]}
Part 2:
In[4]:= dd=Transpose[Partition[cc,2]]
Out[4]= {{a[1],a[2],a[3],a[4],a[5],a[6],a[7]},
{b[1],b[2],b[3],b[4],b[5],b[6],b[7]}}
Note: This works if Length[aa] == Length[bb]. If not dummy elements
should be added.
Cheers, Vittorio