Re: Mapping tag-value lists to a third
- To: mathgroup at smc.vnet.net
- Subject: [mg132455] Re: Mapping tag-value lists to a third
- From: Carl K Woll <carlw at wolfram.com>
- Date: Thu, 20 Mar 2014 05:27:25 -0400 (EDT)
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- References: <20140317062731.30FA06A09@smc.vnet.net>
On 3/17/2014 1:27 AM, carlos.felippa%colorado.edu at gtempaccount.com wrote: > Hi, > > I have 2 lists of equal length such as > > tag={0, 1, 0, 0, 0, 1, 0, 1}; val={f1,f2,f3,f4,f5,f6,f7,f8} > > and want to produce a third: > > tagval={f2,f6,f8} > > with length Count[tag,1] containing the entries of val marked by 1-tags. Should be > something efficient, since the source lists may be large (10^6 to 10^7). Thanks. > I think Pick is what you want: In[366]:= Pick[val, tag, 1] Out[366]= {f2, f6, f8} Carl Woll
- References:
- Mapping tag-value lists to a third
- From: carlos.felippa%colorado.edu@gtempaccount.com
- Mapping tag-value lists to a third