Question

I have a data.frame with 2 columns dates=dates of observations for each station and values=observation data

> head(dataset.a)

     dates      values
1 1976-01-01       7.5
2 1976-01-02        NA
3 1976-01-03        NA
4 1976-01-04        NA
5 1976-01-05        NA
6 1976-01-06      10.2
(...)

I have to multiply each row by a value that I have already from another data.frame:

> head(dataset.b)

     dates      values
1 1976-01-01      0.23
2 1976-01-02        NA
3 1976-01-03        NA
4 1976-01-04        NA
5 1976-01-05        NA
6 1976-01-06      1.23
(...)

Both datasets contain the Gregorian Calendar, however the dataset.a contains
Leap years (adds a 29th day to February) and the dataset.b has always 28 days in February. I want to ignore all 29th days of February in dataset.a and make the multiplication.

I should be able to make a basic subset using both indices:

which(strftime(dataset.a[,1],"%d")!="29")
which(strftime(dataset.a[,1],"%m")!="02")

However once I add a logical AND I loose the position in the data.frame were I have YEAR-02-29 and he returns me the number of rows that are TRUE for the combination of both indices.

I guess this is a very basic question, but I am lost.

Answer 1

Try a logical index:

idx <- strftime(ws.hb1.dataset[d,1],"%d")!="29" & strftime(ws.hb1.dataset[d,1],"%m")!="02"

Note: I’m assuming ws.hb1.dataset[d,1] is basically dataset.a[,1] here?

Then you’ll get a vector of TRUE TRUE ... TRUE FALSE TRUE TRUE .. with the FALSE coinciding with 29/Feb.

Then you can just do dataset.a[idx,] to get the non 29/Feb dates.