CODEWITHSUNDEEP
rlistdataframe
tomsu
tomsu

Reputation: 375

merge two data frames to single object of lists

I would like to create specific object based of 2 data frames. First contains basic information about students, second information how many points each student get in each day.

students <- data.frame(
  studentId = c(1,2,3),
  name      = c('Sophia', 'Mike', 'John'),
  age       = c(13,12,15)
)

studentPoints <- data.frame(
  studentId = c(1,1,1,1,1,2,2,2,2,2,3,3,3,3,3),
  date      = rep(c(Sys.Date()+c(1:5)),3),
  point     = c(5,1,3,9,9,9,5,2,4,5,8,9,5,8,4)
)

As a result I would like to get object:

result <- list(
  list(
    studentId = 1,
    name      = 'Sophia',
    age       = 13,
    details   = list(
      date  = c("2021-04-11", "2021-04-12", "2021-04-13", "2021-04-14", "2021-04-15"),
      point = c(5,1,3,9,9)
    )
  ),
  list(
    studentId = 2,
    name      = 'Mike',
    age       = 12,
    details   = list(
      date  = c("2021-04-11", "2021-04-12", "2021-04-13", "2021-04-14", "2021-04-15"),
      point = c(9,5,2,4,5)
    )
  ),
  list(
    studentId = 3,
    name      = 'John',
    age       = 15,
    details   = list(
      date  = c("2021-04-11", "2021-04-12", "2021-04-13", "2021-04-14", "2021-04-15"),
      point = c(8,9,5,8,4)
    )
  )
)

I created it manually, any idea how to create it automatically? because my database contains few thousands of students

Upvotes: 0

Views: 34

Answers (1)

Ronak Shah
Ronak Shah

Reputation: 388982

Split the lists by studentId, convert each column to it's own list and combine the datasets.

result <- Map(function(x, y) list(x, details = y), 
              lapply(split(students, students$studentId), as.list), 
              lapply(split(studentPoints, studentPoints$studentId), as.list))

Upvotes: 1

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