data.table Long to Wide

Here's an example of converting data from long to wide using the data.table package in R. In data.table, the function we will use is called "dcast"

  

# Load the data.table library
library(data.table)

# Create a long format dataset
long_df <- data.table(
  id = c(1, 2, 3, 1, 2, 3, 1, 2, 3),
  variable = c("x1", "x1", "x1", "x2", "x2", "x2", "x3", "x3", "x3"),
  value = c(10, 20, 30, 40, 50, 60, 70, 80, 90)
)

# Convert to wide format using data.table's dcast function
wide_df <- dcast(long_df, id ~ variable, value.var = "value")

# Show the wide format dataset
print(wide_df)

   id  x1  x2  x3
1:  1  10  40  70
2:  2  20  50  80
3:  3  30  60  90