Passing all variables in a dataframe to expand()

[GreyMerchant]

Hello,

I want to be able to pass all variables into the second argument of expand() without writing all of the variables out. I was hoping I could do something like a full stop or !! but I am not exactly finding the right way to pass it on.

library(tidyverse)

df_initial <- data_frame(V1 = c(0,1),
                      V2 = c(0,1),
                      V3 = c(0,1),
                      V4 = c(0,1),
                      V5 = c(0,1),
                      V6 = c(0,1),
                      V7 = c(0,1),
                      V8 = c(0,1),
                      V9 = c(0,1)
)

df_all_combinations <- tidyr::expand(df_initial,V1,V2,V3,V4,V5,V6,V7,V8,V9)

[mattwarkentin]

Hi @GreyMerchant,

Are you trying to get all possible combinations for all variables? The function expand.grid() should help with this.

expand.grid(df_initial)

You can also use the purrr function cross_df()

purrr::cross_df(df_initial)

[GreyMerchant]

Thanks! This does work as I wanted it to. I would still like to know how to pass the dataframe while getting it to "read" the variables instead if that is at all possible.

[mattwarkentin]

Could you clarify what you mean by "I would still like to know how to pass the dataframe while getting it to "read" the variables instead"? I am not sure what exactly this means.

[GreyMerchant]

Is there a way within expand() to only pass in the dataframe while getting it evaluated as all variables within the dataframe without writing each variable explicitly out?

I know that expand.grid() deals with this problem directly but I was wondering if there is some standard evaluation way of passing a dataframe while only evaluating the variables in that specific object.

[mattwarkentin]

No, currently you are not able to do this. In fact, I submitted an issue to the tidyr GitHub several months ago requesting this very feature. See here for more details.

[GreyMerchant]

Thanks for sharing! I look forward to this addition.