问题
Let's say I have created the following matrix:
> x <- matrix(1:20000,nrow=100)
> x[1:10,1:10]
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 1 101 201 301 401 501 601 701 801 901
[2,] 2 102 202 302 402 502 602 702 802 902
[3,] 3 103 203 303 403 503 603 703 803 903
[4,] 4 104 204 304 404 504 604 704 804 904
[5,] 5 105 205 305 405 505 605 705 805 905
[6,] 6 106 206 306 406 506 606 706 806 906
[7,] 7 107 207 307 407 507 607 707 807 907
[8,] 8 108 208 308 408 508 608 708 808 908
[9,] 9 109 209 309 409 509 609 709 809 909
[10,] 10 110 210 310 410 510 610 710 810 910
What are the methods in R to change row and column names? For example, I like row names to be SS1, SS2, ..., SS100 and column names to be M1, M2, ..., M200. I usually work with data with 1000s of rows and columns, and I need a good method to do that. Some people use something like attributes(x)$dimnames <- list(...) and some use rownames <- paste(...). What are all possible methods?
My second question is, can I use the same methods after I convert the matrix to a data frame?
回答1:
From comment to answer:
row.names(x) <- paste("SS", 1:nrow(x), sep="")
colnames(x) <- paste("M" , 1:ncol(x), sep="")
As @doug wrote, it works for matrices and data frames.
回答2:
Yes same methods will work (matrix/data.frame)--see below:
A = matrix(1:12, nrow=4)
colnames(A) = c("col1", "col2", "col3")
row.names(A) = c("row1", "row2", "row3", "row4")
dfA = as.data.frame(A)
row.names(dfA) = c("r1", "r2", "r3", "r4")
colnames(A) = c("C1", "C2", "C3")
And to save time, you can do this:
x = rep("col", dim(M)[2])
y = 1:dim(M)[2]
colnames(M) = paste(x, y, sep="")
回答3:
If it is within a list you can do.
dimnames(x)[[1]]<-paste("SS", 1:nrow(x), sep="")
dimnames(x)[[2]]<-paste("M" , 1:ncol(x), sep="")
来源：https://stackoverflow.com/questions/2296451/changing-dimnames-of-matrices-and-data-frames-in-r