Combine many data frames into one data frame

This pair of functions binds together data frames (and vectors), either row-wise or column-wise. Row-binding creates a data frame with common type across all arguments. Column-binding creates a data frame with common length across all arguments.

Usage

vec_rbind(
  ...,
  .ptype = NULL,
  .names_to = rlang::zap(),
  .name_repair = c("unique", "universal", "check_unique"),
  .name_spec = NULL
)

vec_cbind(
  ...,
  .ptype = NULL,
  .size = NULL,
  .name_repair = c("unique", "universal", "check_unique", "minimal")
)

Arguments

...

Data frames or vectors.

When the inputs are named:

vec_rbind() assigns names to row names unless .names_to is supplied. In that case the names are assigned in the column defined by .names_to.
vec_cbind() creates packed data frame columns with named inputs.

NULL inputs are silently ignored. Empty (e.g. zero row) inputs will not appear in the output, but will affect the derived .ptype.

.ptype

If NULL, the default, the output type is determined by computing the common type across all elements of ....

Alternatively, you can supply .ptype to give the output known type. If getOption("vctrs.no_guessing") is TRUE you must supply this value: this is a convenient way to make production code demand fixed types.

.names_to

This controls what to do with input names supplied in ....

By default, input names are zapped.
If a string, specifies a column where the input names will be copied. These names are often useful to identify rows with their original input. If a column name is supplied and ... is not named, an integer column is used instead.
If NULL, the input names are used as row names.

.name_repair

One of "unique", "universal", or "check_unique". See vec_as_names() for the meaning of these options.

With vec_rbind(), the repair function is applied to all inputs separately. This is because vec_rbind() needs to align their columns before binding the rows, and thus needs all inputs to have unique names. On the other hand, vec_cbind() applies the repair function after all inputs have been concatenated together in a final data frame. Hence vec_cbind() allows the more permissive minimal names repair.

.name_spec

A name specification (as documented in vec_c()) for combining the outer inputs names in ... and the inner row names of the inputs. This only has an effect when .names_to is set to NULL, which causes the input names to be assigned as row names.

.size

If, NULL, the default, will determine the number of rows in vec_cbind() output by using the standard recycling rules.

Alternatively, specify the desired number of rows, and any inputs of length 1 will be recycled appropriately.

Value

A data frame, or subclass of data frame.

If ... is a mix of different data frame subclasses, vec_ptype2()

will be used to determine the output type. For vec_rbind(), this will determine the type of the container and the type of each column; for vec_cbind() it only determines the type of the output container. If there are no non-NULL inputs, the result will be data.frame().

Invariants

All inputs are first converted to a data frame. The conversion for 1d vectors depends on the direction of binding:

For vec_rbind(), each element of the vector becomes a column in a single row.
For vec_cbind(), each element of the vector becomes a row in a single column.

Once the inputs have all become data frames, the following invariants are observed for row-binding:

vec_size(vec_rbind(x, y)) == vec_size(x) + vec_size(y)
vec_ptype(vec_rbind(x, y)) = vec_ptype_common(x, y)

Note that if an input is an empty vector, it is first converted to a 1-row data frame with 0 columns. Despite being empty, its effective size for the total number of rows is 1.

For column-binding, the following invariants apply:

vec_size(vec_cbind(x, y)) == vec_size_common(x, y)
vec_ptype(vec_cbind(x, y)) == vec_cbind(vec_ptype(x), vec_ptype(x))

Dependencies

vctrs dependencies

base dependencies of `vec_rbind()`

base::c()

If columns to combine inherit from a common class, vec_rbind() falls back to base::c() if there exists a c() method implemented for this class hierarchy.

Examples

# row binding -----------------------------------------

# common columns are coerced to common class
vec_rbind(
  data.frame(x = 1),
  data.frame(x = FALSE)
)
#>   x
#> 1 1
#> 2 0

# unique columns are filled with NAs
vec_rbind(
  data.frame(x = 1),
  data.frame(y = "x")
)
#>    x    y
#> 1  1 <NA>
#> 2 NA    x

# null inputs are ignored
vec_rbind(
  data.frame(x = 1),
  NULL,
  data.frame(x = 2)
)
#>   x
#> 1 1
#> 2 2

# bare vectors are treated as rows
vec_rbind(
  c(x = 1, y = 2),
  c(x = 3)
)
#>   x  y
#> 1 1  2
#> 2 3 NA

# default names will be supplied if arguments are not named
vec_rbind(
  1:2,
  1:3,
  1:4
)
#> New names:
#> • `` -> `...1`
#> • `` -> `...2`
#> New names:
#> • `` -> `...1`
#> • `` -> `...2`
#> • `` -> `...3`
#> New names:
#> • `` -> `...1`
#> • `` -> `...2`
#> • `` -> `...3`
#> • `` -> `...4`
#>   ...1 ...2 ...3 ...4
#> 1    1    2   NA   NA
#> 2    1    2    3   NA
#> 3    1    2    3    4

# column binding --------------------------------------

# each input is recycled to have common length
vec_cbind(
  data.frame(x = 1),
  data.frame(y = 1:3)
)
#>   x y
#> 1 1 1
#> 2 1 2
#> 3 1 3

# bare vectors are treated as columns
vec_cbind(
  data.frame(x = 1),
  y = letters[1:3]
)
#>   x y
#> 1 1 a
#> 2 1 b
#> 3 1 c

# if you supply a named data frame, it is packed in a single column
data <- vec_cbind(
  x = data.frame(a = 1, b = 2),
  y = 1
)
data
#>   x.a x.b y
#> 1   1   2 1

# Packed data frames are nested in a single column. This makes it
# possible to access it through a single name:
data$x
#>   a b
#> 1 1 2

# since the base print method is suboptimal with packed data
# frames, it is recommended to use tibble to work with these:
if (rlang::is_installed("tibble")) {
  vec_cbind(x = tibble::tibble(a = 1, b = 2), y = 1)
}
#> # A tibble: 1 × 2
#>     x$a    $b     y
#>   <dbl> <dbl> <dbl>
#> 1     1     2     1

# duplicate names are flagged
vec_cbind(x = 1, x = 2)
#> New names:
#> • `x` -> `x...1`
#> • `x` -> `x...2`
#>   x...1 x...2
#> 1     1     2