On Sat, 27 Mar 2010, Economics Guy wrote:
I am revising a program that I wrote when I was very new at R
(2007ish), and while I have been able to write very nice and fast code
for almost all of it, there is one issue that I cannot seem to do it
in less than 40 ugly and computationally expensive lines.
I have a data frame that contains one variable:
theFrame <- data.frame(theValues=runif(150,-10,10))
I would like to write a function that would assign each of these
values a factor, and I need it to meet several criteria:
(1) There are 15 factors.
(2) I need there to be exactly 10 elements assigned to each factor.
Now here is the tricky part:
(3) I would like to assign the factor probabilistically. The lower
theValue is for a row, the lower factor I would like it to receive. So
values close to -10 should have a really high probability of being
assigned factor 1.
If assigning factors is to tricky I would settle for placing theValues
in a 10 x 15 matrix where the lower values would be more likely to end
up in column 1 (again, values close to -10 should have a really high
probability of being assigned to column 1.).
It is really the same thing. One of many possibilities:
theFrame <- data.frame(theValues=runif(150,-10,10))
exact <- diag(15)[1+ (rank(theFrame$theValues)-1)%/%10,]
not.so.exact <- diag(15)[1+ (rank(theFrame$theValues+runif(150,0,3))-1)%/%10,]
If what you actually wanted was one factor with fifteen levels, just wrap
the subscript in the last assignment in factor() instead.
HTH,
Chuck
Any ideas? I have thought at times I was painfully close only to
realize I was completely wrong.
Thanks,
That Economics Guy
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Charles C. Berry (858) 534-2098
Dept of Family/Preventive Medicine
E mailto:cbe...@tajo.ucsd.edu UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901
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