HI,
If you have more than one observation per month, you could do this:
dat1<-read.table(text="
Year Month??? Sales??? Customer
2011??? Jan??? 150???? 35
2011??? Jan??? 125???? 40
2011??? Feb??? 130???? 45
2011??? Feb??? 135???? 25
2012??? Jan??? 100???? 25
2012??? Jan??? 150???? 35
2012??? Feb??? 118???? 45
2012??? Feb??? 120???? 30
2012??? Mar??? 130???? 43
2012??? Mar??? 125???? 35
",sep="",header=TRUE,stringsAsFactors=FALSE)
res<-aggregate(.~Year+Month,data=dat1,mean)
?within(res,{Avrev<-Sales/Customer})
#? Year Month Sales Customer??? Avrev
#1 2011?? Feb 132.5???? 35.0 3.785714
#2 2012?? Feb 119.0???? 37.5 3.173333
#3 2011?? Jan 137.5???? 37.5 3.666667
#4 2012?? Jan 125.0???? 30.0 4.166667
#5 2012?? Mar 127.5???? 39.0 3.269231
A.K.
----- Original Message -----
From: Paolo Donatelli <donatellipaolo at gmail.com>
To: r-help at r-project.org
Cc:
Sent: Wednesday, January 9, 2013 11:02 AM
Subject: [R] Basic loop programming
Hi all,
newbie question: I am trying to set up a very simple loop without succeeding.
Let's say I have monthly observation of two variables for a year
- Sales_2012_01, Sales_2012_02, Sales_2012_03, ....? ? ? (total sales
for jan 2012,feb 2012, etc.)
- Customers_2012_01, Customers_2012_02, ....? (total number of
customers for jan 2012, etc.)
and I want to create new monthly variables in order to compute
revenues per customers:
Av_revenue_2012_01 = Sales_2012_01 / Customers_2012_01
Av_revenue_2012_02 = Sales_2012_02 / Customers_2012_02
...
how can I proceed?
In other programming language I used just to write something like
for (i in list("01","02, ..., "12") {
Av_revenue_2012_'i' = Sales_2012_'i' / Customers_2012_'i'
}
but in R it seems not to work like that. Further, and correct me if I
am wrong, I cannot use simple (i in 1:12) since I have a 0 digit in
front of the single-digit months.
thanks in advance for your help
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