On Fri, 1 Oct 2010, Dimitri Liakhovitski wrote:
Hello!
In the example below the Reduce() function by default assigns "a" to
be the last accumulated value and "b" to be the current value in "x".
I could not find this documented anywhere as the default settings for
the Reduce() function. Does any sort of documentation for this
behavior exist?
Yes.
Under 'Details' on the Reduce help page:
"... a left reduce computes l_1 = f(v_1, v_2), l_2 = f(l_1, v_3),
etc..."
HTH,
Chuck
x <- c(0,0,0,0,0,1,0,0,0,5,0,0,0,7,0,0,0,8,5,10)
Reduce(function(a,b) b + (a * 0.5),x,accumulate=T,init=0)
[1] 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000
1.0000000 0.5000000 0.2500000
[10] 0.1250000 5.0625000 2.5312500 1.2656250 0.6328125 7.3164062
3.6582031 1.8291016 0.9145508
[19] 8.4572754 9.2286377 14.6143188
Thanks a lot!
--
Dimitri Liakhovitski
Ninah Consulting
www.ninah.com
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Charles C. Berry (858) 534-2098
Dept of Family/Preventive Medicine
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