tidyr (version 0.6.1)

unnest: Unnest a list column.

Description

If you have a list-column, this makes each element of the list its own row. List-columns can either be atomic vectors or data frames. Each row must have the same number of entries.

Usage

unnest(data, ..., .drop = NA, .id = NULL, .sep = NULL)

Arguments

data

A data frame.

...

Specification of columns to nest. Use bare variable names or functions of variables. If omitted, defaults to all list-cols.

.drop

Should additional list columns be dropped? By default, unnest will drop them if unnesting the specified columns requires the rows to be duplicated.

.id

Data frame idenfier - if supplied, will create a new column with name .id, giving a unique identifer. This is most useful if the list column is named.

.sep

If non-NULL, the names of unnested data frame columns will combine the name of the original list-col with the names from nested data frame, separated by .sep.

See Also

nest for the inverse operation.

unnest_ for a version that uses regular evaluation and is suitable for programming with.

Examples

library(dplyr)
df <- data_frame(
  x = 1:3,
  y = c("a", "d,e,f", "g,h")
)
df %>%
  transform(y = strsplit(y, ",")) %>%
  unnest(y)

# Or just
df %>%
  unnest(y = strsplit(y, ","))

# It also works if you have a column that contains other data frames!
df <- data_frame(
  x = 1:2,
  y = list(
   data_frame(z = 1),
   data_frame(z = 3:4)
 )
)
df %>% unnest(y)

# You can also unnest multiple columns simultaneously
df <- data_frame(
 a = list(c("a", "b"), "c"),
 b = list(1:2, 3),
 c = c(11, 22)
)
df %>% unnest(a, b)
# If you omit the column names, it'll unnest all list-cols
df %>% unnest()

# Nest and unnest are inverses
df <- data.frame(x = c(1, 1, 2), y = 3:1)
df %>% nest(y)
df %>% nest(y) %>% unnest()

# If you have a named list-column, you may want to supply .id
df <- data_frame(
  x = 1:2,
  y = list(a = 1, b = 3:4)
)
unnest(df, .id = "name")