Hi Rick, I guess it's intentional: Matthew saw this SO question (since he edited one of the answers): http://stackoverflow.com/questions/9547518/creating-a-data-frame-where-a-column-is-a-list
Some musings: Of course, to reproduce as.data.frame-like behavior, you can un-nest the list, so both functions treat it the same way. Z <- unlist(Y,recursive=FALSE) identical(as.data.table(Z),as.data.table(as.data.frame(Z))) # TRUE # or, equivalently (?) identical(do.call(data.table,Z),data.table(do.call(data.frame,Z))) # TRUE On the other hand, going back the other direction (getting data.table-like behavior when data.frame's is the default) is more awkward, as seen in that SO question (where they mention protecting each sublist with the I() function). Besides, I'm with @flodel, who asked the SO question, in expecting data.table's behavior: one top-level item in the list mapping to one column in the result... --Frank On Wed, Aug 7, 2013 at 4:56 PM, Ricardo Saporta < [email protected]> wrote: > Hi all, > > Note the following discrepancy in structure between as.data.frame & > as.data.table when called on a nested list. > as.data.frame converts the sublist into individual columns whereas > as.data.table stacks them into a single column and creates additional rows. > > Is this intentional? > -Rick > > > as.data.frame(X) > # start type end data.editDist data.second > # 1 start_node is_similar end_node 1 HelloWorld > > as.data.table(X) > # start type end data > # 1: start_node is_similar end_node 1 > # 2: start_node is_similar end_node HelloWorld > > > > > ### Copy+Paste'able Below ### > > # Example 1: > X <- structure(list(start = "start_node", type = "is_similar", end = > "end_node", > data = structure(list(editDist = 1, second = "HelloWorld"), .Names = > c("editDist", > "second"))), .Names = c("start", "type", "end", "data")) > > as.data.frame(X) > as.data.table(X) > > as.data.table(as.data.frame(X)) > > > # Example 2, with more elements: > Y <- structure(list(start = c("start_node", "start_node"), type = > c("is_similar", "is_similar"), end = c("end_node", "end_node"), data = > structure(list(editDist = c(1, 1), second = c("HelloWorld", "HelloWorld")), > .Names = c("editDist", "second"))), .Names = c("start", "type", "end", > "data")) > > as.data.frame(Y) > as.data.table(Y) > > > _______________________________________________ > datatable-help mailing list > [email protected] > https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help >
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