R Video Tutorial #1: Working with dates and times with plot.ly

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In this video I show you how you can make nice interactive charts with the plot.ly package in R. I go over some issues I ran into regarding how plot.ly interacts with different date formats. Beneath the video you can find the code to reproduce it yourself and the necessary data here.

The video:

The code:



#read in the data with fread from data.table
data <- data.table::fread("sunrise_vienna_2019_zamg.csv", encoding = "UTF-8")

#rename the columns
colnames(data) <- c("Day", "Month", "Year", "sunrise", "sunset", "moonrise", "moonset")

#use mgsub to rename the german months with numbers
data$Month <- textclean::mgsub(data$Month, unique(data$Month), seq(1:12))

#make a new column with the whole date, this uses data.table
data[, date := lubridate::dmy(paste(data$Day, data$Month, data$Year, sep="-"))]

#transform the time from character to a date-time format
data$sunrise <- as.POSIXct(data$sunrise, format = "%H:%M")
data$sunset <- as.POSIXct(data$sunset, format = "%H:%M")

# #lubridate doesn't work with the y-axis of plotly
# data$sunrise <- lubridate::hm(data$sunrise)
# data$sunset <- lubridate::hm(data$sunset)

#calculate the length of days and round them so they have no digits
data$day_length <- round(data$sunset - data$sunrise, 0)

#start preparing the plot
daylength_plot <- plot_ly(data = data, x = ~date, y = ~sunrise, mode = "lines", type = "scatter", 
        #we name the first line (sunrise) and edit the info for the mousover and change
        #the color and "thickness" of the line
        name = "Sunrise", line=list(width=5, color = "#ffca7c"),
        #text that is shown on the mouseover
        hoverinfo = "text", text = ~paste0("Date: ", date ,
                                           "\n", "Sunrise: ", format(sunrise, "%H:%M") ,
                                           "\n", "Sunset: ", format(sunset, "%H:%M"),
                                           "\n", "Length of Day: ", day_length)
) %>%
  #we add the second line (sunset), name it and set color and "thickness"
  add_trace(y = ~sunset, mode = 'lines', name = "Sunset", 
            line=list(width=5, color = "#d4916e")
  ) %>%
  #we add the length of the days as vertical lines
  add_segments(x = ~date, xend = ~date, y = ~sunrise, yend = ~sunset, name = "Length of Day",
               line=list(width=0.5, color = "#ffca7c")
  ) %>%
  #we set some global options for the whole plot
  layout(title = "Length of Days in Vienna 2019",
         xaxis = list(title = "Date"),
         yaxis = list(title = "Time of Day", 
                      #we revers the y-axis so the mornings are on top
                      autorange = "reversed", 
                      #we set the y-axis to date so it correctly maps the variable
                      type = "date", 
                      #we also set the ticks so they correctly map the hours and minutes

#for publishing the plot on plot.ly we set our username and api key
# Sys.setenv("plotly_username"="YOURUSERNAME")
# Sys.setenv("plotly_api_key"="YOURAPIKEY")
# api_create(daylength_plot, filename = "daylength_vienna_2019", sharing = "public",
#            fileopt = "overwrite")

The chart:

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