While a tibble can have row names (e.g., when converting from a regular data
frame), they are removed when subsetting with the [ operator.
A warning will be raised when attempting to assign non-NULL row names
to a tibble.
Generally, it is best to avoid row names, because they are basically a
character column with different semantics than every other column.
These functions allow to you detect if a data frame has row names
(has_rownames()), remove them (remove_rownames()), or convert
them back-and-forth between an explicit column (rownames_to_column()
and column_to_rownames()).
Also included is rowid_to_column(), which adds a column at the start of the
dataframe of ascending sequential row ids starting at 1. Note that this will
remove any existing row names.
Usage
has_rownames(.data)
remove_rownames(.data)
rownames_to_column(.data, var = "rowname")
rowid_to_column(.data, var = "rowid")
column_to_rownames(.data, var = "rowname")Value
column_to_rownames() always returns a data frame.
has_rownames() returns a scalar logical.
All other functions return an object of the same class as the input.
Examples
# Detect row names ----------------------------------------------------
has_rownames(mtcars)
#> [1] TRUE
has_rownames(trees)
#> [1] FALSE
# Remove row names ----------------------------------------------------
remove_rownames(mtcars) %>% has_rownames()
#> [1] FALSE
# Convert between row names and column --------------------------------
mtcars_tbl <- rownames_to_column(mtcars, var = "car") %>% as_tibble()
mtcars_tbl
#> # A tibble: 32 × 12
#> car mpg cyl disp hp drat wt qsec vs am gear carb
#> <chr> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 Mazd… 21 6 160 110 3.9 2.62 16.5 0 1 4 4
#> 2 Mazd… 21 6 160 110 3.9 2.88 17.0 0 1 4 4
#> 3 Dats… 22.8 4 108 93 3.85 2.32 18.6 1 1 4 1
#> 4 Horn… 21.4 6 258 110 3.08 3.22 19.4 1 0 3 1
#> 5 Horn… 18.7 8 360 175 3.15 3.44 17.0 0 0 3 2
#> 6 Vali… 18.1 6 225 105 2.76 3.46 20.2 1 0 3 1
#> 7 Dust… 14.3 8 360 245 3.21 3.57 15.8 0 0 3 4
#> 8 Merc… 24.4 4 147. 62 3.69 3.19 20 1 0 4 2
#> 9 Merc… 22.8 4 141. 95 3.92 3.15 22.9 1 0 4 2
#> 10 Merc… 19.2 6 168. 123 3.92 3.44 18.3 1 0 4 4
#> # … with 22 more rows
column_to_rownames(mtcars_tbl, var = "car") %>% head()
#> 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
# Adding rowid as a column --------------------------------------------
rowid_to_column(trees) %>% head()
#> rowid Girth Height Volume
#> 1 1 8.3 70 10.3
#> 2 2 8.6 65 10.3
#> 3 3 8.8 63 10.2
#> 4 4 10.5 72 16.4
#> 5 5 10.7 81 18.8
#> 6 6 10.8 83 19.7