nrow
The Number of Rows/Columns of an Array
nrow and ncol return the number of rows or columns
present in x.
NCOL and NROW do the same treating a vector as
1-column matrix.
- Keywords
- array
Usage
nrow(x)
ncol(x)
NCOL(x)
NROW(x)Arguments
- x
- a vector, array or data frame
Value
References
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
The New S Language.
Wadsworth & Brooks/Cole (ncol and nrow.)
See Also
Examples
library(base)
ma <- matrix(1:12, 3, 4)
nrow(ma) # 3
ncol(ma) # 4
ncol(array(1:24, dim = 2:4)) # 3, the second dimension
NCOL(1:12) # 1
NROW(1:12) # 12
Community examples
For matrices, nrow and ncol return the number of rows and columns. ```{r} m <- matrix(1:12, 3, 4) nrow(m) # 3 ncol(m) # 4 ``` `NROW()` and `NCOL()` behave exactly the same way. ```{r} m <- matrix(1:12, 3, 4) NROW(m) # 3 NCOL(m) # 4 ``` The same is true for data frames. ```{r} d <- data.frame(a = 1:3, b = 4:6, c = 7:9, d = 10:12) nrow(d) # 3 ncol(d) # 4 ``` For arrays, `nrow()` and `ncol()` refer to the first and second dimensions respectively. ```{r} a <- array(1:24, dim = 2:4) nrow(a) # 2 ncol(a) # 3 ``` For objects without a dim attribute, like vectors, `nrow ()` and `ncol()` are` NULL`, but `NROW()` and `NCOL()` treat the input like a column vector. ```{r} v <- 1:12 nrow(v) # NULL ncol(v) # NULL NROW(v) # 12 NCOL(v) # 1 ``` Note that objects with length zero (and no dim attribute) still have an `NCOL` of 1. ```{r} NROW(NULL) # 0 NCOL(NULL) # 1 ``` Functions have an `NROW` and `NCOL` of 1 (not the number of lines of code in the function body). ```{r} NROW(var) # 1 NCOL(var) # 1 ```