R通过4个坐标选择矩阵

Question

So, for example, I have this matrix in R :

example <- matrix(1:25, nrow = 5)
#     [,1] [,2] [,3] [,4] [,5]
#[1,]    1    6   11   16   21
#[2,]    2    7   12   17   22
#[3,]    3    8   13   18   23
#[4,]    4    9   14   19   24
#[5,]    5   10   15   20   25

I want to select from example matrix from 2:2 to 4:4. How can I do this? Expected result is:

#     [,1] [,2] [,3]
#[1,]    7   12   17
#[2,]    8   13   18
#[3,]    9   14   19

Answer 1

We can use row/column index, ie selecting rows from 2nd to 4th and columns from 2nd to 4th.

example[2:4, 2:4]
#     [,1] [,2] [,3]
#[1,]    7   12   17
#[2,]    8   13   18
#[3,]    9   14   19