Re: Help to clarify 'Map', 'Apply', and 'Thread'.
- To: mathgroup at smc.vnet.net
- Subject: [mg15713] Re: Help to clarify 'Map', 'Apply', and 'Thread'.
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Fri, 5 Feb 1999 03:42:13 -0500 (EST)
- References: <795386$kd1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Ersek, Ted R wrote in message <795386$kd1 at smc.vnet.net>...
>As I said at the beginning the third argument of Thread can be an
>integer (positive or negative) or a list of such integers, but I don't
>know what this might do for you.
Ted,
Hope these examples will help:
Make h[ f threads through elements of f[..] with head h ] ( all other
elements of f[..] regarded as atomic)
In[1]:=
Thread[
h[1, 2],
k[1, 2],
h[1, 2]
],
h
]
Out[1]=
h[
f[1, k[1, 2], 1],
f[2, k[1, 2], 2]
]
Make h[ f threads through elements of f[..] with head h that are in
positions 1 through 2] ( all other elements of f[..] regarded as
atomic)
In[2]:=
Thread[
h[1, 2],
k[1, 2],
h[1, 2]
],
h,
{1,2}
]
Out[2]=
h[
f[1, k[1, 2], h[1, 2]],
f[2, k[1, 2], h[1, 2]]
]
Elements threaded through must be of same length.
In[3]:=
Thread[f[h[1, 2], h[1]], h]
Thread::"tdlen": "Objects of unequal length in \!\(f[\(\(h[\(1, 2\)]\),
\ \(h[1]\)\)]\) cannot be combined."
Out[3]=
f[h[1, 2], h[1]]
Allan
---------------------
Allan Hayes
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