Iterate through a list help

*To*: mathgroup at smc.vnet.net*Subject*: [mg77187] Iterate through a list help*From*: Nick <hoffmannick at gmail.com>*Date*: Tue, 5 Jun 2007 06:48:49 -0400 (EDT)

Hello! I'm (somewhat) new to Mathematica and I need help to iterating through a list and counting the occurrence of a number. My list looks like: {{1,0},{1,1},{2,x+x^2+x^4},{2,1+x+x^2+x^4},{4,x+x^2},{4,1+x+x^2},{4,x +x^4},{4,1+x+x^4}, {4,x^2+x^4},{4,1+x^2+x^4},{4,x^3+x^4},{4,1+x^3+x^4},{4,x+x^2+x^3+x^4}, {4,1+x+x^2+x^3+x^4}, {5,x+x^3},{5,1+x+x^3},{5,x^2+x^3},{5,1+x^2+x^3},{5,x+x^3+x^4},{5,1+x +x^3+x^4},{5,x^2+x^3+x^4}, {5,1+x^2+x^3+x^4},{8,x},{8,x^2},{8,x^3},{8,x^4},{8,1+x},{8,1+x^2}, {8,1+x^3},{8,x+x^2+x^3},{8,1+x+x^2+x^3},{8,1+x^4}} The number that I would need to keep track of is the first in each sub- list. So for the first couple {{1,0},{1,1},{2,x+x^2+x^4},{2,1+x+x^2+x^4}, {4,x +x^2},........ I would need to keep track of 1,1,2,2,4........ It will not always be 1,2,4,5,8's. The numbers may be completely different on each pass. Each sublist may be composed of more items but the number that I need to keep track of will always be the 1st in the sub-list. Any help or suggestions that you can give me will be greatly appreciated. Thanks so much!