Benjamin M. Osborne
2005-Jan-25 22:31 UTC
[R] chron: parsing dates into a data frame using a forloop
I have one data frame with a column of dates and I want to fill another data frame with one column of dates, one of years, one of months, one of a unique combination of year and month, and one of days, but R seems to have some problems with this. My initial data frame looks like this (ignore the NAs in the other fields):> mans[1:10,]date loc snow.new prcp tmin snow.dep tmax 1 11/01/54 2 NA NA NA NA NA 2 11/02/54 2 NA NA NA NA NA 3 11/03/54 2 NA NA NA NA NA 4 11/04/54 2 NA NA NA NA NA 5 11/05/54 2 NA NA NA NA NA 6 11/06/54 2 NA NA NA NA NA 7 11/07/54 2 NA NA NA NA NA 8 11/08/54 2 NA NA NA NA NA 9 11/09/54 2 NA NA NA NA NA 10 11/10/54 2 NA NA NA NA NA>The code and resultant data frame look like this:> for(i in 1:10){+ mans.met$date[i]<-mans$date[i] + mans.met$year[i]<-years(mans.met$date[i]) + mans.met$month[i]<-months(mans.met$date[i]) + mans.met$yearmo[i]<-cut(mans.met$date[i], "months") + mans.met$day[i]<-days(mans.met$date[i]) + }> mans.met[1:10,]date year month yearmo day snow.new snow.dep prcp tmin tmax tmean 1 11/01/54 1 11 1 1 NA NA NA NA NA NA 2 11/02/54 1 11 1 2 NA NA NA NA NA NA 3 11/03/54 1 11 1 3 NA NA NA NA NA NA 4 11/04/54 1 11 1 4 NA NA NA NA NA NA 5 11/05/54 1 11 1 5 NA NA NA NA NA NA 6 11/06/54 1 11 1 6 NA NA NA NA NA NA 7 11/07/54 1 11 1 7 NA NA NA NA NA NA 8 11/08/54 1 11 1 8 NA NA NA NA NA NA 9 11/09/54 1 11 1 9 NA NA NA NA NA NA 10 11/10/54 1 11 1 10 NA NA NA NA NA NA>The problem seems to be with assigning within the forloop, or making the assignment into a data frame, since:> years(mans.met$date[5])[1] 1954 Levels: 1954> test<-years(mans.met$date[5]) > test[1] 1954 Levels: 1954> > months(mans.met$date[5])[1] Nov 12 Levels: Jan < Feb < Mar < Apr < May < Jun < Jul < Aug < Sep < ... < Dec> test<-months(mans.met$date[5]) > test[1] Nov 12 Levels: Jan < Feb < Mar < Apr < May < Jun < Jul < Aug < Sep < ... < Dec> > cut(mans.met$date[3], "months")[1] Nov 54 Levels: Nov 54> test<-cut(mans.met$date[3], "months") > test[1] Nov 54 Levels: Nov 54> > days(mans.met$date[4])[1] 4 31 Levels: 1 < 2 < 3 < 4 < 5 < 6 < 7 < 8 < 9 < 10 < 11 < 12 < 13 < ... < 31> test<-days(mans.met$date[4]) > test[1] 4 31 Levels: 1 < 2 < 3 < 4 < 5 < 6 < 7 < 8 < 9 < 10 < 11 < 12 < 13 < ... < 31>Any suggestions will be appreciated. -Ben Osborne -- Botany Department University of Vermont 109 Carrigan Drive Burlington, VT 05405 benjamin.osborne at uvm.edu phone: 802-656-0297 fax: 802-656-0440
Gabor Grothendieck
2005-Jan-26 04:28 UTC
[R] chron: parsing dates into a data frame using a forloop
Benjamin M. Osborne <Benjamin.Osborne <at> uvm.edu> writes:
:
: I have one data frame with a column of dates and I want to fill another data
: frame with one column of dates, one of years, one of months, one of a unique
: combination of year and month, and one of days, but R seems to have some
: problems with this. My initial data frame looks like this (ignore the NAs in
: the other fields):
:
: > mans[1:10,]
: date loc snow.new prcp tmin snow.dep tmax
: 1 11/01/54 2 NA NA NA NA NA
: 2 11/02/54 2 NA NA NA NA NA
: 3 11/03/54 2 NA NA NA NA NA
: 4 11/04/54 2 NA NA NA NA NA
: 5 11/05/54 2 NA NA NA NA NA
: 6 11/06/54 2 NA NA NA NA NA
: 7 11/07/54 2 NA NA NA NA NA
: 8 11/08/54 2 NA NA NA NA NA
: 9 11/09/54 2 NA NA NA NA NA
: 10 11/10/54 2 NA NA NA NA NA
: >
:
: The code and resultant data frame look like this:
:
: > for(i in 1:10){
: + mans.met$date[i]<-mans$date[i]
: + mans.met$year[i]<-years(mans.met$date[i])
: + mans.met$month[i]<-months(mans.met$date[i])
: + mans.met$yearmo[i]<-cut(mans.met$date[i], "months")
: + mans.met$day[i]<-days(mans.met$date[i])
: + }
: > mans.met[1:10,]
: date year month yearmo day snow.new snow.dep prcp tmin tmax tmean
: 1 11/01/54 1 11 1 1 NA NA NA NA NA NA
: 2 11/02/54 1 11 1 2 NA NA NA NA NA NA
: 3 11/03/54 1 11 1 3 NA NA NA NA NA NA
: 4 11/04/54 1 11 1 4 NA NA NA NA NA NA
: 5 11/05/54 1 11 1 5 NA NA NA NA NA NA
: 6 11/06/54 1 11 1 6 NA NA NA NA NA NA
: 7 11/07/54 1 11 1 7 NA NA NA NA NA NA
: 8 11/08/54 1 11 1 8 NA NA NA NA NA NA
: 9 11/09/54 1 11 1 9 NA NA NA NA NA NA
: 10 11/10/54 1 11 1 10 NA NA NA NA NA NA
: >
:
: The problem seems to be with assigning within the forloop, or making the
: assignment into a data frame, since:
:
: > years(mans.met$date[5])
: [1] 1954
: Levels: 1954
: > test<-years(mans.met$date[5])
: > test
: [1] 1954
: Levels: 1954
: >
: > months(mans.met$date[5])
: [1] Nov
: 12 Levels: Jan < Feb < Mar < Apr < May < Jun < Jul < Aug
< Sep < ... < Dec
: > test<-months(mans.met$date[5])
: > test
: [1] Nov
: 12 Levels: Jan < Feb < Mar < Apr < May < Jun < Jul < Aug
< Sep < ... < Dec
: >
: > cut(mans.met$date[3], "months")
: [1] Nov 54
: Levels: Nov 54
: > test<-cut(mans.met$date[3], "months")
: > test
: [1] Nov 54
: Levels: Nov 54
: >
: > days(mans.met$date[4])
: [1] 4
: 31 Levels: 1 < 2 < 3 < 4 < 5 < 6 < 7 < 8 < 9 < 10
< 11 < 12 < 13 < ... < 31
: > test<-days(mans.met$date[4])
: > test
: [1] 4
: 31 Levels: 1 < 2 < 3 < 4 < 5 < 6 < 7 < 8 < 9 < 10
< 11 < 12 < 13 < ... < 31
: >
:
: Any suggestions will be appreciated.
: -Ben Osborne
I guess you set up mans.met as numeric columns and when you
assign your factors to numeric variables you get
the underlying codes. Note that if f is a factor then as.numeric(f)
gives the codes underlying the factor whereas as.character(f) gives
the labels.
It would be better not to use a loop at all. I don't know whether you
want or not want factors but at any rate here is something you could
try. It creates data frame df2 without a loop.
df2 <- data.frame(date = mans$date, yearmo = as.character(cut(mans$date,
"m")))
df2 <- cbind(df2, month.day.year(mans$date))
Finally, do you really want this redundant representation? I would tend to
go with just storing the dates and computing any of the other quantities
on-the-fly as needed.