adply() does not work with mean() or median() function

[tht18]

adply() does not seem to work consistently. It does not work with some functions (i.e., mean(), median()) but does work with other functions (sum(), sd()) when applying to the same df of numeric values.

df = tibble(x = 1:10, y = 1:10)
plyr::adply(df, 1, mean)
x y V1
1 1 1 NA
2 2 2 NA
3 3 3 NA
4 4 4 NA
5 5 5 NA
6 6 6 NA
7 7 7 NA
8 8 8 NA
9 9 9 NA
10 10 10 NA
Warning messages:
1: In mean.default(piece, ...) :
argument is not numeric or logical: returning NA
2: In mean.default(piece, ...) :
argument is not numeric or logical: returning NA
3: In mean.default(piece, ...) :
argument is not numeric or logical: returning NA
4: In mean.default(piece, ...) :
argument is not numeric or logical: returning NA
5: In mean.default(piece, ...) :
argument is not numeric or logical: returning NA
6: In mean.default(piece, ...) :
argument is not numeric or logical: returning NA
7: In mean.default(piece, ...) :
argument is not numeric or logical: returning NA
8: In mean.default(piece, ...) :
argument is not numeric or logical: returning NA
9: In mean.default(piece, ...) :
argument is not numeric or logical: returning NA
10: In mean.default(piece, ...) :
argument is not numeric or logical: returning NA

plyr::adply(df, 1, median)
Error in median.default(piece, ...) : need numeric data

But works with sum():

plyr::adply(df, 1, sum)
x y V1
1 1 1 2
2 2 2 4
3 3 3 6
4 4 4 8
5 5 5 10
6 6 6 12
7 7 7 14
8 8 8 16
9 9 9 18
10 10 10 20

or sd():

plyr::adply(df, 1, sd)
x y V1
1 1 1 0
2 2 2 0
3 3 3 0
4 4 4 0
5 5 5 0
6 6 6 0
7 7 7 0
8 8 8 0
9 9 9 0
10 10 10 0