R Lesson 21: Calendar Plots

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Hello everybody,

Michael here, and today’s post will be an R lesson on calendar plots in R. Now I know I already did a lesson on dates and times in R, but this lesson will focus on creating cool calendar plots in R with the calendR package.

Before we start making calendar plots, let’s install the calendR package.

Once we install these packages, let’s start by building a simple calendar plot with this line of code-calendR(). Here’s the output we get:

As you can see, the calendR() prints out a calendar for the current year (2020). If no parameter is specified, calendR() print the current year’s calendar by default.

If you want to print the calendar for a different year, specify the year in the parameter. Let’s say you wanted to print last year’s calendar (2019). To print last year’s calendar, use this line of code-calendR (year=2019). Here’s the output from that line of code:

OK, now let’s try some other neat calendar tricks. First, let’s set up our calendar plot to have weeks start on Monday (weeks start on Sunday by default). Here’s the code to do so:

calendR(start="M")

Since I didn’t specify a year in the parameter, calendR will print out a calendar of the current year by default.

Awesome! Now let’s add some color to certain special days. Here’s the code to do so:

calendR(special.days = c(61,91,121,331,360,366), special.col="lightgreen", low.col="white")

When adding color to certain special days, here are some things to keep in mind:

  • The calendR function has its own parameter to denote special days-aptly named special.days. Special.col specifies a color for the special days while low.col specifies a color for all other days.
  • To choose which days to highlight, specify the corresponding number for the day you want to highlight (e.g. 1 corresponds to January 1, 2 to January 2, and so on). Remember that if the calendar plot is for a leap year (like the plot above), day numbers from March 1 onward will be different than they would be in a non-leap year (e.g. the day number for March 2 in a non-leap year would be 61, while in a leap year it would be 62).

Now what if we wanted to highlight all of the weekends? Let’s see how we can do that. Use this line of code to highlight the weekends in 2020:

calendR(special.days="weekend")

Now what if we wanted to add several color-coded events to the calendar? Here’s the code to do that:

events <- rep(NA, 366) 
events[1] <- "Holidays"
events[45] <- "Holidays"
events[146] <- "Holidays"
events[186] <- "Holidays"
events[251] <- "Holidays"
events[305] <- "Holidays"
events[331] <- "Holidays"
events[360] <- "Holidays"
events[366] <- "Holidays"
events[61] <- "My Birthday"
calendR(special.days=events, special.col=c("green", "orange"), legend.pos="right")

How did I create this calendar plot? Let me give you a step-by-step breakdown:

  • In order to add events to the calendar plot, you would first need to create a vector of NA values. My vector is called events, but the name of the vector doesn’t matter. Just remember to make the vector the same length of the number of days of days as the corresponding year.
    • Hint-the vector will have a length of 366 for leap years (such as 2020) and 365 for non-leap years (such as 2021)
  • Next, add all of the events you want on the calendar to the corresponding day of the year on the vector. For example, two days I wanted to highlight were January 1 and May 25 (New Year’s Day and Memorial Day 2020, respectively), so I added these two days to positions 1 and 146 of the events vector, as January 1 and May 25 were the 1st and 146th days of 2020, respectively.
    • If you want multiple dates under the same event category (e.g. “Holidays” in this example) , you’ll have to list all of the corresponding days of the year in the vector 1-by-1, unless the dates are consecutive (e.g. an event that goes on for 7 consecutive days). You can’t list all of the corresponding days of the year in a comma-separated array like you can in Java or Python (I know because I tried to do this and it didn’t work).
  • Once you added all of the events to the calendar, use the calendR function to create the color-coded calendar plot with events. The function takes four parameters, which include:
    • year-the year for the calendar plot; if a year isn’t specified, calendR will create a plot of the current year by default (as it does in this example)
    • special.days-the vector of events you created (events in this example)
    • special.col-the colors to represent each of the events
      • Only use as many colors as you have event categories. In this example, I only have two event categories-“My Birthday” and “Holidays”-and thus only use two colors for this function. Also keep in mind that the first color listed will be used for the first event category, the second color for the second event category, and so on.
    • legend.pos-the positioning of the legend on the plot; in this example, legend.pos equals right, which means that the legend will be displayed on the right of the graph

Now, what if you wanted to make a calendar plot for just a single month? Using the current month as an example, here’s how to do so:

calendR(month = 12)

By simply using the code calendR(year = X, month = 1-12) you can create a calendar plot for any month of any year. Remember that if you don’t specify the year, calendR will create a plot for chosen month of the current year (2020) by default.

Great, now let’s add some color to certain days! Here’s the code to do that (along with the corresponding output):

calendR(month = 12, special.days=c(9, 16, 25, 27, 31), special.col="yellow", low.col="white")

OK, what if we wanted to add several color-coded events to the calendar? Let’s see how we can do this:

events2 <- rep(NA, 31)
events2[24:25] <- "Holidays"
events2[31] <- "Holidays"
events2[1:4] <- "Workweek"
events2[16] <- "Birthdays"
events2[27] <- "Birthdays"
calendR(month = 12, special.days=events2, special.col = c("red", "orange", "lightblue"), low.col="white", legend.pos="top")

The process for adding color-coded events for a month-long calendar plot is the same as it is for a year-long calendar plot, except you would need to make the events vector the length of the days in the month rather than the length of the days in the year. In this case the length of the events vector (called events2 to avoid confusion with the other events vector) would be 31, as there are 31 days in December.

  • Just so you know, low.col in the last two examples refers to the color of the boxes that don’t contain color-coded events.

Great, now let’s say we wanted to add some text to the days. How would we go about this? Here’s how:

calendR(month = 12, text=c("Battlebots", "Birthday", "Christmas", "Birthday", "New Year's Eve"), text.pos=c(3, 16, 25, 27, 31), text.size=4.5, text.col="green4")

Here’s a step-by-step breakdown of how I created this plot:

  • First, I indicated the month I wanted to use for my calendar plot. Since I didn’t specify a year, calendR will automatically plot the chosen month of the current year (December 2020).
  • Next, I created a vector of text I wanted to add to the calendar plot and used text.pos to indicate which days should contain which text (for instance, the first element in the text vector corresponds with the first element of the text.pos vector).
    • Remember to keep the text vector the same size as the text.pos vector.
    • I know this sounds obvious, but know how many days the month on your calendar plot has, or else the calendar plot won’t work. For instance, trying to place text on 32 in this plot won’t work because December doesn’t have a 32nd.
  • Text.size and text.col specify the font size and color of the text, respectively.

Now let’s try something different-creating a lunar calendar, which is a month-long calendar plot that shows the different moon phases on each day of the month. Also, just out of curiosity, let’s create a lunar calendar for next month-here’s the code to do so:

calendR(year = 2021, month = 1, lunar = TRUE, lunar.col="gray60", lunar.size=8)

Here’s a step-by-step breakdown of how I created this lunar calendar:

  • Since I’m creating this lunar calendar for next month, I had to specify both the year (2021) and the month (1), as next month is the January 2021 (crazy, huh).
  • I had to set lunar to TRUE to indicate that this is a lunar calendar
  • Lunar.col signifies the color of the non-visible area of the moons.
  • Lunar.size signifies the size of the moons on the calendar plot.
  • In case you’re wondering what each of the moon phases are, here’s a handy little graphic (feel free to Google this information if you want to learn more about moon phases):

Last but not least, let me show you how we can create a calendar plot with custom start and end dates. A perfect example of this type of calendar plot would be an academic calendar, which I will show you how to create below, using the 2020-21 Metro Nashville Public Schools calendar as an example:

events3 <- rep(NA, 304)
events3[3] <- "Day Off"
events3[6] <- "Day Off"
events3[38] <- "Day Off"
events3[63] <- "Day Off"
events3[66:70] <- "Day Off"
events3[73] <- "Day Off"
events3[84] <- "Day Off"
events3[95] <- "Day Off"
events3[103] <- "Day Off"
events3[117:119] <- "Day Off"
events3[140] <- "Day Off"
events3[143:147] <- "Day Off"
events3[150:154] <- "Day Off"
events3[157:159] <- "Day Off"
events3[171] <- "Day Off"
events3[199] <- "Day Off"
events3[227:231] <- "Day Off"
events3[238] <- "Day Off"
events3[245] <- "Day Off"
events3[299] <- "Day Off"
events3[4] <- "First & Last Days of School"
events3[298] <- "First & Last Days of School"
events3[136:139] <- "Half Days"
events3[293:294] <- "Half Days"
events3[297] <- "Half Days" 

calendR(start_date = "2020-08-01", end_date = "2021-05-31", special.days=events3, special.col=c("salmon", "seagreen1", "gold"), legend.pos="right", title = "Metro Nashville Public Schools 2020-21 Calendar")

So, how did I create this color-coded calendar plot with a custom start and end date? Here’s a step-by-step breakdown of the process:

  • Since I knew the start and end dates I wanted to use for this calendar plot, I created an events vector (named events3 to avoid confusion with the other two events vectors) of length 304. My start and end dates are August 1, 2020 and May 31, 2021, respectively, which cover a 304 day period (including the end date).
  • I then added all of the events to the corresponding days on the vector. Since this isn’t a standard calendar year vector, knowing which element corresponds to which day is trickier. However, I created an excel table with the dates in my date range on one column and the corresponding day in the other column, like this:
  • After inserting all of the events to the corresponding days in the vector, I then used the calendR function to indicate my start_date and end_date.
  • For the special.days argument, I used the events3 vector I created.
  • I then indicated the three colors I wanted to use for the three event categories as the argument for special.col
    • For special.col remember to include the same amount of colors as event categories in this vector. Since I had 3 event categories, I used 3 colors in this vector.
  • I then set legend.pos to right, which tells calendR to place the legend to the right of the calendar plot.
  • Lastly, I set the title of the plot to Metro Nashville Public Schools 2020-21 Calendar.

Thanks for reading,

Michael

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