Message-ID: <6E8D8DFDE5FA5D4ABCB8508389D1BF8802BDDB5D@SRVEXCHMBX.precheza.cz>
Date: 2014-08-01T13:17:40Z
From: PIKAL Petr
Subject: How to avoid the three loops in R?
In-Reply-To: <CACB+=LigevswvBUUzxo09sUgZDDtPwu6YHTKzJYig2vRm_Fg2A@mail.gmail.com>
Hi
I do not see any solution without loops but maybe others find it.
I think that you can do it in one loop. Best structure for loop will be list.
In each cycle you will compute matrix with diagonal NA
mat<-matrix(1,nrow=number of items, ncol=number of items)
diag(mat) <- NA
apply(price chunk * mat, 2, mean, na.rm=T)
So when I named your example as temp I get
fac <- interaction(factor(temp$Product), factor(temp$Year_Month), drop=T)
lll <- split(temp, fac)
for( i in 1:length(lll)) {
mat <- matrix(1, nrow=nrow(lll[[i]]), ncol= nrow(lll[[i]]))
diag(mat) <- NA
lll[[i]]$others <- apply(mat*lll[[i]][,3], 2, mean, na.rm=T)
}
> lll
$`1.201204`
Country Product Price Year_Month others
1 AE 1 20 201204 24
2 DE 1 20 201204 24
3 CN 1 28 201204 20
$`2.201204`
Country Product Price Year_Month others
4 AE 2 28 201204 25
5 DE 2 28 201204 25
6 CN 2 22 201204 28
$`3.201204`
Country Product Price Year_Month others
7 AE 3 28 201204 28
8 CN 3 28 201204 28
$`1.201205`
Country Product Price Year_Month others
9 AE 1 20 201205 24
10 DE 1 20 201205 24
11 CN 1 28 201205 20
$`2.201205`
Country Product Price Year_Month others
12 AE 2 28 201205 28
13 DE 2 28 201205 28
I did not check speed but it shall be OK.
Regards
Petr
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Lingyi Ma
> Sent: Friday, August 01, 2014 1:42 PM
> To: r-help at r-project.org
> Subject: [R] How to avoid the three loops in R?
>
> I have the following data set:
>
> Country Product Price Year_Month
> AE 1 20 201204
> DE 1 20 201204
> CN 1 28 201204
> AE 2 28 201204
> DE 2 28 201204
> CN 2 22 201204
> AE 3 28 201204
> CN 3 28 201204
> AE 1 20 201205
> DE 1 20 201205
> CN 1 28 201205
> AE 2 28 201205
> DE 2 28 201205
>
> I want to create the one more column which is "The average price of the
> product in other areas".
> in other word, for each month, for each product, I calculate the
> average of such product in the other area.
>
> I want sth like:
>
> Country Product Price Year_Month Price_average_In_Other_area
> AE 1 20 201204 14
> AE 2 28 201204 25
>
> Please avoid the three for loop, I have tried and it never end. I have
> 1070427 rows. Is there better way to speed up my program?
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-
> guide.html
> and provide commented, minimal, self-contained, reproducible code.
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