Summary: List element manipulation
- To: mathgroup at smc.vnet.net
- Subject: [mg25467] Summary: List element manipulation
- From: "Martin Rommel" <rommel at semitest.com>
- Date: Sun, 1 Oct 2000 02:44:54 -0400 (EDT)
- References: <8r19qf$hvt@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Thanks to the many helpful people that replied with their insight.
The straightforward fix to my problematic
> MapAt[Decrement, Range[116, 166, 8], -1]
>
> Decrement::"rvalue": "164 is not a variable with a value, so its value
> cannot be changed."
is using a function # - 1& instead of Decrement (which is not a mathematical
function but instead listed under programming assignments in the help
browser)
MapAt[# - 1&, Range[116, 166, 8], -1]
This was suggested by the news group veterans David Park, Andrzej Kozlowski,
Hartmut Wolf and Allan Hayes.
Matt Johnson suggested an alternative using a rule (it is always interesting
to see things done differently)
Range[116, 166, 8] /. {h___, t_} -> {h, t - 1}
Special thanks to Andrzej Kozlowski for additonal explainations but the most
in depth coverage came from my compatriot Hartmut Wolf.
With hindsight I don't understand why I was so fixated on employing
Decrement.
Martin