Re: Clever way to manipulate lists
- To: mathgroup at smc.vnet.net
- Subject: [mg94395] Re: Clever way to manipulate lists
- From: Raffy <raffy at mac.com>
- Date: Thu, 11 Dec 2008 07:28:48 -0500 (EST)
- References: <ghqjve$14i$1@smc.vnet.net>
(* Create some random data *)
list1 = Transpose@{Range[10], RandomInteger[{1, 100}, 10]}
list2 = Transpose@{RandomSample[Range[10], 6], RandomInteger[{101,
200}, 6]}
(* Just for the sake of testing, verify that list2 keys are contained
in list1 *)
Complement[list2[[All, 1]], list1[[All, 1]]]
(* Create a map from list1 keys to values *)
map = Rule @@@ list1
(* Get list2 keys *)
keys = list2[[All, 1]]
(* Map list2 keys to list1 values *)
values = keys /. map
(* Build up a new list1 *)
list1new = Transpose@{keys,values }
Or, as one line: Transpose@{list2[[All, 1]], list2[[All, 1]] /. Rule
@@@ list1}
Dispatch[] can be used if you apply the rules more than once.