R avoid coercion from matrix to numeric [duplicate]

StackOverflow https://stackoverflow.com/questions/12788040

  •  06-07-2021
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Question

Possible Duplicate:
1-dimensional Matrix is changed to a vector in R

I work with matrix objects in R and many times it happens that I want to select only one column of a matrix a use it as a matrix of one column !!! Yes, I mean I don't want R to coerce it automatically to a numeric class because the meaning is a matrix of 1 column in that case. How to avoid R doing this silly conversion all the time at a general level. I don't want to clutter my code with as.matrix everywhere !

Was it helpful?

Solution

Use drop=FALSE

> matrix(1:10, ncol=2)
     [,1] [,2]
[1,]    1    6
[2,]    2    7
[3,]    3    8
[4,]    4    9
[5,]    5   10
> matrix(1:10, ncol=2)[, 2]
[1]  6  7  8  9 10
> matrix(1:10, ncol=2)[, 2, drop=FALSE]
     [,1]
[1,]    6
[2,]    7
[3,]    8
[4,]    9
[5,]   10
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