#I have a data frame with a numeric and a character variable.
x=c(1,2,3,2,0,2,-1,-2,-4)
md=c(rep("Miller",3), rep("Richard",3),rep("Smith",3))
data1=data.frame(x,md)
#I subset this data.frame in a way such that one level of the character
variable does not appear in the new dataset.
data2=data1[x>0,]
data3=subset(data1,x>0)
#However, when I check the levels of the factor variable in the subset data
frame, it still shows the levels that are now unused.
unique(data2$md)
unique(data3$md)
#This leads to complications in table and tapply that I want to avoid.
table(data2$md)
tapply(data2$x,data2$md,mean)
table(data3$md)
tapply(data3$x,data3$md,mean)
#Basically, I want to completely remove "Smith" from data frame data2 or
data3 so that it would not show up in table or tapply operations.
Thanks for any pointers,
Daniel
-----------------------------------------------
"Who has visions, should see a doctor,"
Helmut Schmidt, German Chancellor (1974-1982).
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