Re: Challenge: Fastest method to convert positive integers to 1 in a long list

*To*: mathgroup at smc.vnet.net*Subject*: [mg52195] Re: Challenge: Fastest method to convert positive integers to 1 in a long list*From*: Peter Pein <petsie at arcor.de>*Date*: Sun, 14 Nov 2004 04:31:00 -0500 (EST)*References*: <cn4m4e$19p$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Carl K. Woll wrote: > Hi all, > > Inspired by the recent thread on counting runs, I have the following > challenge. Come up with a method to convert all the positive integers in a > long sequence of nonnegative integers to 1, so that the sequence consists of > only 0s and 1s. Let the sequence be given by > > seq = Table[Random[Integer, 10], {10^6}]; > > Then, one technique is > > newseq = 1+Quotient[#,#+1,1]&@seq; > > Can anyone do better? > > Carl Woll > > Sign[.] is simpler, isn't it? In[1]:= seq = Table[Random[Integer, 10], {10^6}]; In[2]:= t1 = First@Timing[newseq1 = 1 + Quotient[#, # + 1, 1] &@seq;] Out[2]= 0.671 Second In[3]:= t2 = First@Timing[newseq2 = Sign@seq;] Out[3]= 0.12 Second In[4]:= newseq1 == newseq2 t1/t2 Out[4]= True Out[5]= 5.59167 ..it is :-) -- Peter Pein Berlin