[R] keep the row indexes/names when do aggregate
Hi, R-users, If I have a data frame like this: x-data.frame(g=c(g1,g2,g1,g1,g2),v=c(1,7,3,2,8)) g v 1 g1 1 2 g2 7 3 g1 3 4 g1 2 5 g2 8 It contains two groups, g1 and g2. Now for each group I want the max v: aggregate(x$v,list(g=x$g),max) g x 1 g1 3 2 g2 8 Beautiful. But what if I want to keep the row index of (g1 3) and (g2 8) in the original x? So I want is: do something g x 3 g1 3 5 g2 8 Of course it'd may make much more sense if the row indexes are some row names that I want to keep. Is there a simple way to do that? Thanks a lot! Z _ [[elided Hotmail spam]] [[alternative HTML version deleted]] __ R-help@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.
[R] sort a data matrix by all the values and keep the names
Dear all, If I have a data frame x-data.frame(x1=c(1,7),x2=c(4,6),x3=c(8,2)): x1 x2 x3 1 4 8 7 6 2 I want to sort the whole data and get this: x1 1 x3 2 x2 4 x2 6 x1 7 x3 8 If I do sort(X), R reports: Error in order(list(x1 = c(1, 7), x2 = c(4, 6), x3 = c(8, 2)), decreasing = FALSE) : unimplemented type 'list' in 'orderVector1' The only way I can sort all the data is by converting it to a matrix: sort(as.matrix(x)) [1] 1 2 4 6 7 8 But now I lost all the names attributes. Is it possible to sort a data frame and keep all the names? Thanks! Zhihua Li _ [[elided Hotmail spam]] [[alternative HTML version deleted]] __ R-help@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.
Re: [R] sort a data matrix by all the values and keep the names
This is exactly what I wanted! Thank you so much! Z Date: Mon, 22 Sep 2008 19:21:43 -0500 From: [EMAIL PROTECTED] Subject: RE: [R] sort a data matrix by all the values and keep the names To: [EMAIL PROTECTED] Hi: there might be a quicker way but you can use stack and order. stack creates a dataframe with 2 columns, values and ind, with ind being the associate columns. order(temp$values) creates the indices of the ordered values so you index by that to make it sorted. temp - stack(x) print(temp) print(str(temp)) sortedx - temp[order(temp$values),] print(sortedx) On Mon, Sep 22, 2008 at 7:54 PM, zhihuali wrote: Dear all, If I have a data frame x-data.frame(x1=c(1,7),x2=c(4,6),x3=c(8,2)): x1 x2 x3 1 4 8 7 6 2 I want to sort the whole data and get this: x1 1 x3 2 x2 4 x2 6 x1 7 x3 8 If I do sort(X), R reports: Error in order(list(x1 = c(1, 7), x2 = c(4, 6), x3 = c(8, 2)), decreasing = FALSE) : unimplemented type 'list' in 'orderVector1' The only way I can sort all the data is by converting it to a matrix: sort(as.matrix(x)) [1] 1 2 4 6 7 8 But now I lost all the names attributes. Is it possible to sort a data frame and keep all the names? Thanks! Zhihua Li _ [[elided Hotmail spam]] [[alternative HTML version deleted]] __ R-help@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. _ [[elided Hotmail spam]] [[alternative HTML version deleted]] __ R-help@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.
[R] how to use a function in aggregate which accepts matrix and outputs matrix?
Dear netters, suppose I have a matrix X [1,] 'c1' 'r6' '150'[2,] 'c1' 'r4' '70'[3,] 'c1' 'r2' '20'[4,] 'c1' 'r5' '90'[5,] 'c2' 'r2' '20'[6,] 'c3' 'r1' '10'I want to apply some funciton to groups of rows by the first column.If the function is just to calculate the average X[,3], it will be easy: aggregate(as.numeric(X[,3]),by=list(X[,1]),mean)But the function I want to use is more complicated. It will take as input a matrix(X[rows in the same group,c(2,3)], do some computation, and output another matrixwith the dimension (y,3), where y depends on the input. And I'd like the resultto be a rbind of each of the subset outputs. aggregate can not do that because the function is supposed to take vectors and output scalars.How can I apply the complicated function to groups of a matrix? Thanks! Zhihua Li _ Windows Live Photo gallery ÊýÂëÏà»úµÄ³¬¼¶°é£¬ÇáËɹÜÀíºÍ±à¼ÕÕƬ£¬»¹ÄÜÖÆ×÷È«¾°ÃÀͼ£¡ http://get.live.cn/product/photo.html [[alternative HTML version deleted]] __ R-help@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.
[R] locate the rows in a dataframe with some criteria
Hi, netters, This is probably a rookie question but I couldn't find the answer after hours of searching and trying. Suppose there'a a dataframe M: x y 10 A 13 B 8 A 11 A I want to locate the rows where x =10 and y=A. I know how to do it to vectors by using which, but how to do it with the dataframe? Thank you very much! Zhihua Li _ MSN ÖÐÎÄÍø£¬×îÐÂʱÉÐÉú»î×ÊѶ£¬°×Áì¾Û¼¯ÃÅ»§¡£ [[alternative HTML version deleted]] __ R-help@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.
[R] An R clause to bind dataframes under certain contions
Hi netters, Suppose I have two data frames X and Y. X has three colnames A, B and C. Y has three colnames A,B and D. I want to combine them into one matrix, joining the rows having the same A and B values (X$A==Y$A and X$B = Y$B). So the resulting dataframe has four variables/columns: A,B,C and D. I was wondering what's the best way to do it in R. Could anyone give me some advice? Thanks! Zhihua Li _ ÊÖ»úÒ²ÄÜÉÏ MSN ÁÄÌìÁË£¬¿ìÀ´ÊÔÊÔ°É£¡ [[alternative HTML version deleted]] __ R-help@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.
