monitor_getCurrentStatus: Get current status of monitors

Description Usage Arguments Value "Last" and "Previous" Calculating latency Summary data Event flags Examples

View source: R/monitor_getCurrentStatus.R

Description

This function augments the metadata from a ws_monitor object with summarized and aggregate data from the ws_monitor object.

Usage

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monitor_getCurrentStatus(
  ws_monitor,
  endTime = NULL,
  monitorURLBase = "http://tools.airfire.org/monitoring/v4/#!/?monitors="
)

Arguments

ws_monitor

ws_monitor object.

endTime

Time to which the status of the monitors will be current. By default, it is the most recent time in ws_monitor. This time can be given as a POSIXct time, or a string/numeric value in ymd format (eg. 20190301). This time converted to UTC.

monitorURLBase

A URL prefix pointing to where more information about a monitor can be found. By default, it points to the AirFire monitoring site.

Value

A table containing the current status information for all the monitors in ws_monitor.

"Last" and "Previous"

The goal of this function is to provide useful information about what happened recently with each monitor in the provided ws_monitor object. Monitors sometimes don't consistently report data, however, and it's not useful to have NA's reported when there is still valid data at other times. To address this, monitor_getCurrentStatus uses last and previous valid times. These are the time when a monitor most recently reported data, and the most recent time of valid data before that, respectively. By reporting on these times, the function ensures that valid data is returned and provides information on how outdated this information is.

Calculating latency

According to https://docs.airnowapi.org/docs/HourlyDataFactSheet.pdf a datum assigned to 2pm represents the average of data between 2pm and 3pm. So, if we check at 3:15pm and see that we have a value for 2pm but not 3pm then the data are completely up-to-date with zero latency.

monitor_getCurrentStatus() defines latency as the difference in time between the given time index and the next most recent time index. If there is no more recent time index, then the difference is measured to the given endTime parameter. These differences are recorded in hours.

For example, if the recorded values for a monitor are [16.2, 15.8, 16.4, NA, 14.0, 12.5, NA, NA, 13.3, NA], then the last valid time index is 9, and the previous valid time index is 6. The last latency is then 1 (hour), and the previous latency is 3 (hours).

Summary data

The table created by monitor_getCurrentStatus() includes summary information for the data part of the given ws_monitor object. The summaries included are listed below with a description:

yesterday_pm25_24hr

Daily AQI value for the day prior to endTime

last_nowcast_1hr

Last valid NowCast measurement

last_PM2.5_1hr

Last valid raw PM2.5 measurement

last_PM2.5_3hr

Mean of the last valid raw PM2.5 measurementwith the preceding two measurements

previous_nowcast_1hr

Previous valid NowCast measurement

previous_PM2.5_1hr

Previous valid raw PM2.5 measurement

previous_PM2.5_3hr

Mean of the previous valid raw PM2.5 measurement with the preceding two measurements

It should be noted that all averages are "right-aligned", meaning that the three hour mean of data at time n will comprise of the data at times [n-2, n-1, n]. Data for n-2 and n-1 is not guaranteed to exist, so a three hour average may include 1 to 3 data points.

Event flags

The table created by monitor_getCurrentStatus() also includes binary flags representing events that may have occurred for a monitor within the bounds of the specified end time and data in the ws_monitor object. Each flag is listed below with its corresponding meaning:

last_nowcastLevel

NowCast level at the last valid time

previous_nowcastLevel

NowCast level at the previous valid time

NR6

Monitor not reporting for more than 6 hours

NEW6

New monitor reporting in the last 6 hours

USG6

NowCast level increased to Unhealthy for Sensitive Groups in the last 6 hours

U6

NowCast level increased to Unhealthy in the last 6 hours

VU6

NowCast level increased to Very Unhealthy in the last 6 hours

HAZ6

NowCast level increased to Hazardous in the last 6 hours

MOD6

NowCast level decreased to Moderate or Good in the last 6 hours

MAL6

Monitor malfunctioning the last 6 hours (not currently implemented)

Examples

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library(PWFSLSmoke)

ws_monitor <- monitor_loadLatest() %>% monitor_subset(stateCodes = "WA")
statusTbl <- monitor_getCurrentStatus(ws_monitor)

PWFSLSmoke documentation built on July 8, 2020, 7:19 p.m.