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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")

Arguments

.data

A data frame.

var

Name of column to use for rownames.

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
#> # ℹ 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