Convert fractional year and day of year to date in R

Question

Is it possible to convert a fractional year and day of year to an actual date format in R?

For example, in the time column in my example data below, 1900.00 corresponds to January of 1900, 1900.08 corresponds to February. dayofyr corresponds to the year day.

myData <- structure(list(time = c(1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.08, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.17, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.25, 1900.2 5, 1900.25, 1900.25, 1900.25, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.33, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.42, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.5, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 19 00.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.58, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.67, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.75, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.83, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 190 0.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92, 1900.92), dayofyr = 1:366), class = c("tbl_df", "tbl", "data.frame"), row.names = c(NA, -366L), .Names = c("time", "dayofyr"))

Answer 1

使用floor删除小数部分，转换为带"-01-01"字符串，将其转换为"Date"类，然后加上减1的天数。不使用任何包。

transform(myData, date = as.Date(paste0(floor(time), "-01-01")) + dayofyr - 1)