Can you use sapply on specific columns within dplyr?

[cwright1]

library(dplyr)

How can I use sapply on a dataframe within dplyr? I thought I'd just reference the current object at a given line with a . symbol.

#mtcars but with first row equal to mtcars' rownames
mtcars2 <- 
  cbind(data.frame("names"=rownames(mtcars)), mtcars)

#If I want to make columns 2-the end of mtcars numeric, this works:
sapply(mtcars[,2:ncol(mtcars)], as.numeric)

#Does not work in dplyr
mtcars2 %>%
  sapply(.[,2:ncol(.)], as.numeric)

in dplyr the error is :

Error in match.fun(FUN) :
'.[, 2:ncol(.)]' is not a function, character or symbol

[M_AcostaCH]

@cwright1

sapply(mtcars[,2:ncol(mtcars)], as.numeric)

mtcars %>%
  select(-1) %>%
  mutate_all(as.numeric)

[cwright1]

@M_AcostaCH

mtcars %>%
  select(-1) %>%
  mutate_all(as.numeric)

Thanks - but doesn't this lose column 1 in the process? I just want to do the sapply to all columns of mtcars2 except column1 (or use a mutate_all like you have), but i still need the first column. De-selecting the column in this way loses it right?

[M_AcostaCH]

@M_AcostaCH

select(-1)

With this avoid transform the first column. But dont delete it. The others colums are trnasform into numeric.

[cwright1]

But you lose the 1st column:

#mtcars but with first row equal to mtcars' rownames
mtcars2 <- 
  cbind(data.frame("names"=rownames(mtcars)), mtcars)

mtcars3 <- 
  mtcars2 %>%
  select(-1) %>%
  mutate_all(as.numeric)

  head(mtcars3)

                   mpg cyl disp  hp drat    wt  qsec vs am gear carb
Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
Valiant           18.1   6  225 105 2.76 3.460 20.22  1  0    3    1

EDIT:
I guess a way I could do it with select(-1) would be:

  mtcars3 <- 
    cbind(
      mtcars2[,1],
      mtcars2 %>% select(-1) %>% mutate_all(as.numeric)
    )

[nirgrahamuk]

mtcars2 %>%
  mutate(across(.cols = -1,
                .fns = as.numeric))