Example: Hourly Barplot

How can I create an hourly barplot?

If you have AirMonitor installed, you should be able to copy and paste this code into the RStudio console.

The monitor_timeseriesPlot() function can be used to create an hourly barplot as seen on many websites with each bar colored by PM2.5 level. The following code shows how this is done for a single monitor and is ready to paste into RStudio.

Enjoy!

library(AirMonitor)

# Define the monitor_hourlyBarplot() function
monitor_hourlyBarplot <- function(
  monitor = NULL,
  id = NULL,
  shadedNight = FALSE,
  addAQI = FALSE,
  lwd = 3,
  ...
){ 
  # ----- Validate parameters --------------------------------------------------

  MazamaCoreUtils::stopIfNull(monitor)

  # Subset 'monitor' to a single time series
  if ( nrow(monitor$meta) > 1 ) {

    MazamaCoreUtils::stopIfNull(id)
    if ( !id %in% monitor$meta$deviceDeploymentID )
      stop("id = \"%s\" is not found in 'monitor'")

    monitor <-
      monitor %>%
      monitor_filter(.data$deviceDeploymentID == !!id)

  }

  monitor <- monitor_dropEmpty(monitor)

  if ( ncol(monitor$data) < 2 )
    stop("no valid data in 'monitor'")

  if ( nrow(monitor$meta) > 1 )
    stop("multiple records found in 'monitor$meta'")

  # ----- Hourly Barplot -------------------------------------------------------
  
  # Pull out PM2.5 data for colors
  pm2.5 <- monitor$data %>% dplyr::pull(monitor$meta$deviceDeploymentID)
  
  monitor_timeseriesPlot(
    monitor = monitor,
    id = id,
    shadedNight = shadedNight,
    addAQI = addAQI,
    type = 'h',        # bars
    lwd = lwd,         # barplot width
    lend = 1,          # barplot square ends
    col = aqiColors(pm2.5),
    ...
  )
  
}

Now we can put this function to use with some examples:

# Example 1) simple

AirMonitor::Carmel_Valley %>%
  monitor_hourlyBarplot(
    shadedNight = TRUE
  )

# Example 2) recent data for King County, Washington

# Load recent data
airnow <- airnow_loadLatest()
enddate <- lubridate::now("UTC")
startdate <- enddate - lubridate::ddays(3)

airnow %>% 
  # King County Washington
  monitor_filter(stateCode == "WA" & countyName == "King") %>%
  # Trim to last 3 days
  monitor_filterDate(startdate, enddate) %>%
  # Average together hour by hour
  monitor_collapse(FUN = mean) %>%
  # Hourly barplot with enhancements
  monitor_hourlyBarplot(
    main = "Average PM2.5 for King County, Washington",
    shadedNight = TRUE,
    lwd = 5,
    xlab = ''
  )

Jonathan Callahan

2025-09-16