r - Nested list to data frame and back to nested list -


consider nested list data rectangular.

mylst1 <- list(   "system" = list(     "subjectid" = c(101,102,103),     "procedureid" = c(202,202,203)   ),   "demographics" = list(     "demo_age" = c(12,22,32),     "demo_gender" = c(1,0,1)   ),   "items" = list(     "n" = list(       "n001" = c(1,2,3),       "n002" = c(3,2,1)       ),     "e" = list(       "e001" = c(1,2,3),       "e002" = c(3,2,1)     )   ) )

since nested lists awkward work with, let's create data frame: mydf <- data.frame(mylst1)

so far good, can perform operations on mydf. let's assume filtered observations. problem need return same nested list structure required web application want send data to, data of course looks this:

> str(mydf)     'data.frame':   3 obs. of  8 variables:      $ system.subjectid        : num  101 102 103      $ system.procedureid      : num  202 202 203      $ demographics.demo_age   : num  12 22 32      $ demographics.demo_gender: num  1 0 1      $ items.n.n001            : num  1 2 3      $ items.n.n002            : num  3 2 1      $ items.e.e001            : num  1 2 3      $ items.e.e002            : num  3 2 1

what best solution data in original list format? thinking of using . delimiter each level, i'm unsure how in practice.

thanks

one option relist (assuming columns of same class) in 'mydf'

newlst <- relist(unlist(mydf), skeleton = mylst1) identical(mylst1, newlst) #[1] true

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