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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?
905
In a data frame the columns contain different types of data, but in a matrix all the elements are the same type of data. A matrix in R is like a mathematical matrix, containing all the same type of thing (usually numbers). R often but not always lets these be used interchangably.
A matrix can be converted to a dataframe by using a function called as. data. frame(). It will take each column from the matrix and convert it to each column in the dataframe.
Both represent 'rectangular' data types, meaning that they are used to store tabular data, with rows and columns. The main difference, as you'll see, is that matrices can only contain a single class of data, while data frames can consist of many different classes of data.
Naming Rows and Columns of a Matrix in R Programming – rownames() and colnames() Function. rownames() function in R Language is used to set the names to rows of a matrix.
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.
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