[R] cast vs melt

★ [학습목표]
행렬 데이터를 cast, melt 함수를 이용하여 transpose 할 수 있다.

1) cast

• "reshape2" package를 설치하는 것이 필요함.

# Install and load the reshape2 package
install.packages("reshape2")
library(reshape2)

# Create a sample data frame
data <- data.frame(
  ID = c(1, 2, 3, 1, 2, 3),
  Category = c("A", "A", "A", "B", "B", "B"),
  Value = c(10, 20, 30, 40, 50, 60)
)

# Print the original data frame
print("Original data frame:")
print(data)

# Reshape the data from long to wide format using dcast
wide_data <- dcast(data, ID ~ Category, value.var = "Value")

# Print the reshaped data frame
print("Reshaped data frame:")
print(wide_data)

dt_1 <- wide_data
dt_1

dt_1[,c(1,3,2)]

2) melt

# Install and load the reshape2 package
install.packages("reshape2")
library(reshape2)

# Create a sample wide-format data frame
wide_data <- data.frame(
  ID = c(1, 2, 3),
  A = c(10, 20, 30),
  B = c(40, 50, 60),
  C = c(70, 80, 90)
)

# Print the original wide-format data frame
print("Original wide-format data frame:")
print(wide_data)

# Melt the wide-format data frame into long format using melt
long_data <- melt(wide_data, id.vars = "ID")

# Print the melted long-format data frame
print("Melted long-format data frame:")
print(long_data)