How to get sub-list elements at certain position in a long list

• To: mathgroup at smc.vnet.net
• Subject: [mg123071] How to get sub-list elements at certain position in a long list
• From: Gy Peng <hitphyopt at gmail.com>
• Date: Tue, 22 Nov 2011 05:36:37 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

```Dear Experts,

I have a list:

{{{{2.5}, {3.8, 31}, {54.23, 46.263, 45.987}, *{-82.1476,** 5.17782,
-205.36}*}, {{2.5}, {4.2, 30}, {233.835, 46.469,
46.819}, *{93.8625, -13.9818, -198.778}*}}, {{{2.5}, {4.1,30},
{139.845, 15.719, 155.87}, *{93.6633,**4.46398, -205.432}*}, {{2.5}, {2.6,
32}, {113.381, 40.988,85.09}, *{90.1206, 16.9792, -205.314}*}}, {{{2.5},
{3.1,30}, {113.858, 34.709, 87.567}, *{55.3298,**17.7214, -211.648}*},
{{2.5}, {2.7, 30}, {110.54, 31.595,85.601}, *{-25.8558, 175.588, -121.105}*
}}}

How do I get each 4th sublist element in the last level? I mean, I want to
get a list looks like:
{*{-82.1476, **5.17782, -205.36}, **{93.8625, -13.9818, -198.778},**{90.1206,
16.9792, -205.314},**{55.3298,**17.7214, -211.648},**{-25.8558, 175.588,
-121.105}}*
which only includes every 4th element in the last level. Do I describe my
question clearly?

Better not to use any "For", simple Map or Thread method are preferred.

Thank you very much!!!
*
*

```

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