Pivot data from long to wide

Analogous function for pivot_wider in tidyr.

wider_dt(
  data,
  group_to_keep = NULL,
  name_to_spread,
  value_to_spread = NULL,
  fill = NA
)

Arguments

data	data.table
group_to_keep	The unchanged group in the transformation. Could use integer vector, character vector or regular expression(to match the column names). If NULL, use all other variables.
name_to_spread	Chracter.One column name of class to spread
value_to_spread	Chracter.One column name of value to spread. If NULL, use all other variables.
fill	Value with which to fill missing cells. Default uses NA.

Value

data.table

See also

dcast

pivot_wider

Examples

 stocks = data.frame(
   time = as.Date('2009-01-01') + 0:9,
   X = rnorm(10, 0, 1),
   Y = rnorm(10, 0, 2),
   Z = rnorm(10, 0, 4)
 ) %>%
   longer_dt(time) -> longer_stocks

 longer_stocks
#>           time variable       value
#>  1: 2009-01-01        X -0.15569378
#>  2: 2009-01-02        X  0.43388979
#>  3: 2009-01-03        X -0.38195111
#>  4: 2009-01-04        X  0.42418757
#>  5: 2009-01-05        X  1.06310200
#>  6: 2009-01-06        X  1.04871262
#>  7: 2009-01-07        X -0.03810289
#>  8: 2009-01-08        X  0.48614892
#>  9: 2009-01-09        X  1.67288261
#> 10: 2009-01-10        X -0.35436116
#> 11: 2009-01-01        Y  1.89269577
#> 12: 2009-01-02        Y  2.63365271
#> 13: 2009-01-03        Y -0.59328005
#> 14: 2009-01-04        Y -0.77442715
#> 15: 2009-01-05        Y -1.57086531
#> 16: 2009-01-06        Y -2.11347373
#> 17: 2009-01-07        Y -1.59108286
#> 18: 2009-01-08        Y -3.51255086
#> 19: 2009-01-09        Y -1.38107579
#> 20: 2009-01-10        Y -1.11708399
#> 21: 2009-01-01        Z -2.14665331
#> 22: 2009-01-02        Z  0.90850853
#> 23: 2009-01-03        Z  3.91381968
#> 24: 2009-01-04        Z -0.83553061
#> 25: 2009-01-05        Z -5.59764184
#> 26: 2009-01-06        Z  1.03414915
#> 27: 2009-01-07        Z -1.76719781
#> 28: 2009-01-08        Z  2.27439944
#> 29: 2009-01-09        Z  8.50740184
#> 30: 2009-01-10        Z  1.69943377
#>           time variable       value

 longer_stocks %>%
   wider_dt("time","variable","value")
#>           time           X          Y          Z
#>  1: 2009-01-01 -0.15569378  1.8926958 -2.1466533
#>  2: 2009-01-02  0.43388979  2.6336527  0.9085085
#>  3: 2009-01-03 -0.38195111 -0.5932800  3.9138197
#>  4: 2009-01-04  0.42418757 -0.7744272 -0.8355306
#>  5: 2009-01-05  1.06310200 -1.5708653 -5.5976418
#>  6: 2009-01-06  1.04871262 -2.1134737  1.0341492
#>  7: 2009-01-07 -0.03810289 -1.5910829 -1.7671978
#>  8: 2009-01-08  0.48614892 -3.5125509  2.2743994
#>  9: 2009-01-09  1.67288261 -1.3810758  8.5074018
#> 10: 2009-01-10 -0.35436116 -1.1170840  1.6994338

 longer_stocks %>%
   mutate_dt(one = 1) %>%
   wider_dt("time","variable","one")
#>           time X Y Z
#>  1: 2009-01-01 1 1 1
#>  2: 2009-01-02 1 1 1
#>  3: 2009-01-03 1 1 1
#>  4: 2009-01-04 1 1 1
#>  5: 2009-01-05 1 1 1
#>  6: 2009-01-06 1 1 1
#>  7: 2009-01-07 1 1 1
#>  8: 2009-01-08 1 1 1
#>  9: 2009-01-09 1 1 1
#> 10: 2009-01-10 1 1 1