R dplyr rowwise mean or min and other methods?

How can I get with dplyr the minimum (or mean) value of each row on a data.frame? I mean the same result as

apply(mydataframe, 1, mean) 
apply(mydataframe, 1, min)

I've tried

mydataframe %>% rowwise() %>% mean

or

mydataframe %>% rowwise() %>% summarise(mean)

or other combinations but I always get errors, I don't know the proper way.

I know that I could also use rowMeans, but there is no simple "rowMin" equivalent. There also exist a matrixStats package but most functions don't accept data.frames, only matrixes.

If I want to calculate the min rowwise I could use
do.call(pmin, mydataframe) Is there anything simple like this for the rowwise mean?

do.call(mean, mydataframe) 

doesn't work, I guess I need a pmean function or something more complex.

Thanks

In order to compare the results we could all work on the same example:

set.seed(124)
df <- data.frame(A=rnorm(10), B=rnorm(10), C=rnorm(10))

Solution 1:

I suppose this is what you were trying to accomplish:

df <- data.frame(A=rnorm(10), B=rnorm(10), C=rnorm(10))

library(dplyr)
df %>% rowwise() %>% mutate(Min = min(A, B, C), Mean = mean(c(A, B, C)))

#             A          B           C        Min        Mean
# 1   1.3720142  0.2156418  0.61260582  0.2156418  0.73342060
# 2  -1.4265665 -0.2090585 -0.05978302 -1.4265665 -0.56513600
# 3   0.6801410  1.5695065 -2.70446924 -2.7044692 -0.15160724
# 4   0.0335067  0.8367425 -0.83621791 -0.8362179  0.01134377
# 5  -0.2068252 -0.2305140  0.23764322 -0.2305140 -0.06656532
# 6  -0.3571095 -0.8776854 -0.80199141 -0.8776854 -0.67892877
# 7   1.0667424 -0.6376245 -0.41189564 -0.6376245  0.00574078
# 8  -1.0003376 -1.5985281  0.90406055 -1.5985281 -0.56493504
# 9  -0.8218494  1.1100531 -1.12477401 -1.1247740 -0.27885677
# 10  0.7868666  0.6099156 -0.58994138 -0.5899414  0.26894694

Solution 2:

There seems to be talk that some dplyr functions like rowwise could be deprecated in the long term (such rumblings on display here). Instead, certain functions from the map family of functions -- such as the pmap function -- from purrr can be used to perform this sort of calculation:

library(tidyverse)

df %>% mutate(Min = pmap(df, min), Mean = rowMeans(.))

#              A          B           C        Min       Mean
# 1  -1.38507062  0.3183367 -1.10363778  -1.385071 -0.7234572
# 2   0.03832318 -1.4237989  0.44418506  -1.423799 -0.3137635
# 3  -0.76303016 -0.4050909 -0.20495061 -0.7630302 -0.4576905
# 4   0.21230614  0.9953866  1.67563243  0.2123061  0.9611084
# 5   1.42553797  0.9588178 -0.13132225 -0.1313222  0.7510112
# 6   0.74447982  0.9180879 -0.19988298  -0.199883  0.4875616
# 7   0.70022940 -0.1509696  0.05491242 -0.1509696  0.2013907
# 8  -0.22935461 -1.2230688 -0.68216549  -1.223069 -0.7115296
# 9   0.19709386 -0.8688243 -0.72770415 -0.8688243 -0.4664782
# 10  1.20715377 -1.0424854 -0.86190429  -1.042485 -0.2324120

Mean is a special case (hence the use of the base function rowMeans), since mean on data.frame objects was deprecated with R 3.0.

Solution 3:

How about this?

library(dplyr)
as.data.frame(t(mtcars)) %>%
  summarise_all(funs(mean))

For extra clarity, you could add another t() at the end:

as.data.frame(t(mtcars)) %>%
  summarise_all(funs(mean)) %>%
  t()