python - Handle multiple values in column -

consider example data.table package in r:

dt = data.table(id = c("b","b","b","a","a","c"), = 1:6, b = 7:12, c=13:18) dt = dt[, .(a=list(a), b=list(b), c=list(c)), by=id] dt    id         b        c 1:  b 1,2,3 7,8,9 13,14,15 2:    4,5 10,11    16,17 3:  c     6    12       18 

after want write file in order share structure. however, prohibits writing such things write.csv because of list type. solution found convert columns string. however, how can read file? there unified format can read in (almost) language without effort?

you can create tab-seperated file follows:

dt2 <- dt[, .(a=tostring(a), b=tostring(b), c=tostring(c)), by=id] write.table(dt2, "dt2.txt", sep="\t", row.names = false) 

which should readable languages.

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when want preserve lists, transforming json suggested @tigerhawkt3 best option:

dt3 <- dt[, .(a=list(a), b=list(b), c=list(c)), by=id] library(jsonlite) tojson(dt3) 

which gives:

[{"id":"b","a":[1,2,3],"b":[7,8,9],"c":[13,14,15]},{"id":"a","a":[4,5],"b":[10,11],"c":[16,17]},{"id":"c","a":[6],"b":[12],"c":[18]}]