As a lecturer at UC Merced, each semester I find myself needing to figure out how many days I get to teach. Furthermore, I like to plan out my lecture schedule down to the days themselves. Here I hope to use some R code to quickly figure out (say) which days are on Monday, Wednesday, or Friday.


In R, the seq command can be used with dates easily.

fall_dates <- seq(as.Date("2017-08-23"), as.Date("2017-12-08"), by = "days")

When working with time data, the xts package (“extensible time series”) offers convenient tools for manipulating time series.

xts_dates <- as.xts( rep(NA, length(fall_dates)), = fall_dates)

Monday Wednesday Friday

For instance, I want to know the exact dates for each Monday, Wednesday, and Friday of the semester. The convention here is that “0” is a Monday and “7” is a Sunday.

MWF_dates <- xts_dates[.indexwday(xts_dates) %in% c(0, 2, 4)]
##            [,1]
## 2017-08-23   NA
## 2017-08-25   NA
## 2017-08-28   NA
## 2017-08-30   NA
## 2017-09-01   NA
## 2017-09-04   NA

Exporting the Time Series

From here, I might still want to use Excel for data entry in my planning. xts objects are still zoo objects.

write.zoo(MWF_dates, sep = ",", file = "schedule.csv")

Now I have a spreadsheet with the dates already arranged!