nested data.frame [closed] - r

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I have a nested data.frame
dput(res)
structure(list(date = structure(list(pretty = "12:00 PM CDT on August 14, 2015",
year = "2015", mon = "08", mday = "14", hour = "12", min = "00",
tzname = "America/Chicago"), .Names = c("pretty", "year",
"mon", "mday", "hour", "min", "tzname"), class = "data.frame", row.names = 1L),
fog = "0", rain = "1", snow = "0", snowfallm = "0.00", snowfalli = "0.00",
monthtodatesnowfallm = "", monthtodatesnowfalli = "", since1julsnowfallm = "",
since1julsnowfalli = "", snowdepthm = "", snowdepthi = "",
hail = "0", thunder = "0", tornado = "0", meantempm = "26",
meantempi = "79", meandewptm = "17", meandewpti = "63", meanpressurem = "1019",
meanpressurei = "30.09", meanwindspdm = "11", meanwindspdi = "7",
meanwdire = "", meanwdird = "139", meanvism = "16", meanvisi = "10",
humidity = "", maxtempm = "32", maxtempi = "90", mintempm = "21",
mintempi = "69", maxhumidity = "86", minhumidity = "36",
maxdewptm = "18", maxdewpti = "65", mindewptm = "15", mindewpti = "59",
maxpressurem = "1021", maxpressurei = "30.15", minpressurem = "1017",
minpressurei = "30.04", maxwspdm = "19", maxwspdi = "12",
minwspdm = "0", minwspdi = "0", maxvism = "16", maxvisi = "10",
minvism = "16", minvisi = "10", gdegreedays = "29", heatingdegreedays = "0",
coolingdegreedays = "14", precipm = "0.00", precipi = "0.00",
precipsource = "", heatingdegreedaysnormal = "", monthtodateheatingdegreedays = "",
monthtodateheatingdegreedaysnormal = "", since1sepheatingdegreedays = "",
since1sepheatingdegreedaysnormal = "", since1julheatingdegreedays = "",
since1julheatingdegreedaysnormal = "", coolingdegreedaysnormal = "",
monthtodatecoolingdegreedays = "", monthtodatecoolingdegreedaysnormal = "",
since1sepcoolingdegreedays = "", since1sepcoolingdegreedaysnormal = "",
since1jancoolingdegreedays = "", since1jancoolingdegreedaysnormal = ""), .Names = c("date",
"fog", "rain", "snow", "snowfallm", "snowfalli", "monthtodatesnowfallm",
"monthtodatesnowfalli", "since1julsnowfallm", "since1julsnowfalli",
"snowdepthm", "snowdepthi", "hail", "thunder", "tornado", "meantempm",
"meantempi", "meandewptm", "meandewpti", "meanpressurem", "meanpressurei",
"meanwindspdm", "meanwindspdi", "meanwdire", "meanwdird", "meanvism",
"meanvisi", "humidity", "maxtempm", "maxtempi", "mintempm", "mintempi",
"maxhumidity", "minhumidity", "maxdewptm", "maxdewpti", "mindewptm",
"mindewpti", "maxpressurem", "maxpressurei", "minpressurem",
"minpressurei", "maxwspdm", "maxwspdi", "minwspdm", "minwspdi",
"maxvism", "maxvisi", "minvism", "minvisi", "gdegreedays", "heatingdegreedays",
"coolingdegreedays", "precipm", "precipi", "precipsource", "heatingdegreedaysnormal",
"monthtodateheatingdegreedays", "monthtodateheatingdegreedaysnormal",
"since1sepheatingdegreedays", "since1sepheatingdegreedaysnormal",
"since1julheatingdegreedays", "since1julheatingdegreedaysnormal",
"coolingdegreedaysnormal", "monthtodatecoolingdegreedays", "monthtodatecoolingdegreedaysnormal",
"since1sepcoolingdegreedays", "since1sepcoolingdegreedaysnormal",
"since1jancoolingdegreedays", "since1jancoolingdegreedaysnormal"
), class = "data.frame", row.names = 1L)
and I am using the following command to retrieve data from it
df <- data.frame()
df <- rbind(df, ldply(res, function(x) x[[1]]))
To use this data frame, I convert it into data table, using dt <- data.table(df) and now I know how to work with the data, for instance dt[.id=="fog"].
Is there a more elegant/efficient solution?
The problem was solved by #antoine-sac. It was not necessary to use the apply to get the data, it was only a question of "un-nest" the data.

Answer 1

Your problem is that your data is a data.frame and one of its column is date. But date is a data.frame. As you say it is a nested list. So let's "un-nest" it.
You can simply do (assuming your data is in data):
df.date <- data$date
# removing incorrectly formated date from data
data$date <- NULL
At this point, data is a normal data.frame and df.date is also a basic data.frame.
> df.date
pretty year mon mday hour min tzname
1 12:00 PM CDT on August 14, 2015 2015 08 14 12 00 America/Chicago
If you want to merge that with your existing data.frame:
# binding df.date with your data
data <- cbind(data, df.date)
No need for any kind of apply.
Now if you don't know how to access variables in a data.frame, that's another thing.
If you want, say, meantempm, you can simply do data$meantempm.
I refer you to beginner tutorial about R, there are plenty to choose from with a google request.