Re: Counting nonzeros
- To: mathgroup at smc.vnet.net
- Subject: [mg86873] Re: Counting nonzeros
- From: Szabolcs Horvát <szhorvat at gmail.com>
- Date: Tue, 25 Mar 2008 01:13:43 -0500 (EST)
- Organization: University of Bergen
- References: <fs7iml$gma$1@smc.vnet.net>
carlos at colorado.edu wrote: > I want to count the # of NZ entries in an arbitrary multilevel list, > say exp, that contains only integers. Is this the easiest way: > > k = Length[Flatten[exp]]-Count[Flatten[exp],0] Suppose that we only have integers in the list. Count[expr, Except[0, _Integer], Infinity] Instead of _Integer, we could use _Symbol or _?AtomQ or some other pattern depending on the type of elements that need to be counted. (_Integer was necessary to avoid counting all the compound expressions, such as sublists.)