Hi,
Try either:
tolerance <-
read.csv("http://www.ats.ucla.edu/stat/r/examples/alda/data/tolerance1.txt";)
aggregate(exposure~male,data=tolerance,mean)
# male exposure
#1 0 1.246667
#2 1 1.120000
#or
library(plyr)
ddply(tolerance,.(male),summarize,exposure=mean(exposure))
# male exposure
#1 0 1.246667
#2 1 1.120000
#or
with(tolerance,tapply(exposure,list(male),FUN=mean))
# 0 1
#1.246667 1.120000
#or
with(tolerance,by(exposure,list(male),mean))
#: 0
#[1] 1.246667
#------------------------------------------------------------
#: 1
#[1] 1.12
#or
library(data.table)
tolerance1<- data.table(tolerance)
tolerance1[,list(exposure=mean(exposure)),by=male]
# male exposure
#1: 0 1.246667
#2: 1 1.120000
#or
sapply(split(tolerance,tolerance$male),function(x) mean(x$exposure))
# 0 1
#1.246667 1.120000
#or
library(psych)
describeBy(tolerance$exposure,tolerance$male,mat=TRUE)[c(2,5)]
# group1 mean
#11 0 1.246667
#12 1 1.120000
#or
library(doBy)
summaryBy(exposure~male,data=tolerance,FUN=mean)
# male exposure.mean
#1 0 1.246667
#2 1 1.120000
A.K.
>Hi there,
>
>I'm new to R and I think I have hard time getting used to it.
Before asking my question, I looked on several websites, and while they
have many >informations about it, I did not find clear answer to my
question.
>
>So, first of all, I use a web-based data set :
>
>tolerance <-
>read.csv("http://www.ats.ucla.edu/stat/r/examples/alda/data/tolerance1.txt";)
>
>RIght now, I'm able to calculate the mean of the variable
exposure. However, I'm unable to find a parsimonious way of obtaining
the mean of >exposure, separately for male == 0 and male == 1. The only
solution I have, for the moment, is:
>
>
>tolerance_male = tolerance [male ==0, c (1:8)]
>exposure_male = tolerance_male$exposure
>mean (tolerance_male$exposure)
>
>
>tolerance_female = tolerance [male ==1, c (1:8)]
>exposure_female = tolerance_female$exposure
>mean (exposure_female)
>
>While this method work well for a simple calculation, it'll be
quite unhelpful for more complicated analysis. So, I don't know if
someone has a simpler >way to do it.
>
>Thank you!
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