How to transpose a dataframe in tidyverse?

Question

Using basic R, I can transpose a dataframe, say mtcars, which has all columns of the same class:

as.data.frame(t(mtcars))

Or with pipes:

library(magrittr)
mtcars %>% t %>% as.data.frame

How to accomplish the same within tidyr or tidyverse packages?

My attempt below gives:

Error: Duplicate identifiers for rows

library(tidyverse)
mtcars %>% gather(var, value, everything()) %>% spread(var, value)

Emersen

If you want to transpose it it should be a matrix and not a data.frame. What's wrong with using t? – Fieldfare

Try add_rownames(mtcars) %>% gather(var, value, -rowname) %>% spread(rowname, value) – Kliman

Why do you want to do this? You cannot meaningfully transpose a data.frame that contains many variable classes without loss of information. – Inofficious

A data frame, such as mtcars, might have all columns of the same class. – Emersen

Answer 1

Try with add_rownames

add_rownames(mtcars) %>% 
         gather(var, value, -rowname) %>% 
         spread(rowname, value) 

In the newer version, rownames_to_column replaces add_rownames

mtcars %>%
   rownames_to_column %>% 
   gather(var, value, -rowname) %>% 
   spread(rowname, value) 

In the even newer version, pivot_wider replaces spread:

mtcars %>%
   tibble::rownames_to_column() %>%  
   pivot_longer(-rowname) %>% 
   pivot_wider(names_from=rowname, values_from=value) 

Kliman

Thanks @akrun. Looks like add_rownames is depreciated, but this works: mtcars %>% rownames_to_column %>% gather(var, value, -rowname) %>% spread(rowname, value) – Emersen

Rows in the transformed data are by default ordered (alphabetically the mtcars case). If you want to order the rows according to the initial column order (i.e. names(mtcars)) an additional step is required: mtcars.t[order(match(mtcars.t$var,names(mtcars))),], where mtcars.t is the transformed data. – Lambda

just after i hit submit i realized that gather() is now pivot_longer() :/ – Telangiectasis

Puuh, that's pretty code intense as compared to t(). Seems like something on the to do list for the next dplyr version. – Eyecatching

Answer 2

There's now a purpose-built function to do this, rotate_df() from sjmisc.

library(sjmisc)
mtcars %>% rotate_df()

#     Mazda RX4 Mazda RX4 Wag Datsun 710 Hornet 4 Drive Hornet Sportabout Valiant Duster 360
#mpg      21.00        21.000      22.80         21.400             18.70   18.10      14.30
#cyl       6.00         6.000       4.00          6.000              8.00    6.00       8.00
#disp    160.00       160.000     108.00        258.000            360.00  225.00     360.00
#hp      110.00       110.000      93.00        110.000            175.00  105.00     245.00
#drat      3.90         3.900       3.85          3.080              3.15    2.76       3.21

#etc

The function also allows you to convert rownames to real df data with the rotate. Many thanks to the package creators.

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