Q: efficient list operation wanted

*To*: mathgroup at smc.vnet.net*Subject*: [mg13973] Q: efficient list operation wanted*From*: Klaus Duellmann <k.duellmann at uni-mannheim.deXXX>*Date*: Fri, 11 Sep 1998 15:07:01 -0400*Organization*: Rechenzentrum Uni Mannheim*Sender*: owner-wri-mathgroup at wolfram.com

I am looking for an efficient solution of the following problem: Given two lists L1 = {1,2,3,4,5,3,7,2,3,9} and L2 = {a, b, c} I want to replace all numbers 3 in L1 by the elements of L2 successively, that is the first 3 by a, the second 3 by b and the third 3 by c. That is I want to get the following modified L1-list: {1,2,a,4,5,b,7,2,c,9}. Replace[] unfortunately replaces elements with a single element only. Is there a chance to avoid hideous Do-Loops? Any hints are appreciated! PS. Remove XXX from my e-mail-address K. Duellmann

**Follow-Ups**:**Re: Q: efficient list operation wanted***From:*Jurgen Tischer <jtischer@col2.telecom.com.co>