aggregate(df$treatment, list(gp=df$group, dup=df$duplicate), mean)
hope this helps. spencer graves
Marc Schwartz wrote:
On Wed, 2003-10-01 at 20:15, [EMAIL PROTECTED] wrote:
Hello, R experts:
I got data like this:
group duplicate treatment A Y 5
A Y 3
A N 6
B Y 2
B N 4
B Y 1
How to sort the data and calculate the average treatment value for each group in two level of duplicate. Results like this:
group duplicate treatment A Y 4
A N 6
B Y 1.5
B N 4
Thank you in advance.
Josh
# Create a dataframe
df <- data.frame(group = c(rep("A", 3), rep("B", 3)), duplicate = c("Y", "Y", "N", "Y", "N", "Y"), treatment = c(5, 3, 6, 2, 4, 1))
# Use aggregate aggregate(df$treatment, list(df$group, df$duplicate), mean) Group.1 Group.2 x 1 A N 6.0 2 B N 4.0 3 A Y 4.0 4 B Y 1.5
Aggregate returns a data frame in this case, so that you can then set the colnames and order the output if you wish.
HTH,
Marc Schwartz
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