generate_alerts: Execute the alert task

Description

Evaluate alerts for the last collected day for all topics and regions and send email alerts to subscribers

Usage

generate_alerts(tasks = get_tasks())

Value

The list of tasks updated with produced messages

Arguments

tasks: Current tasks for reporting purposes, default: get_tasks()

Details

This function calculates alerts for the last aggregated day and then send emails to subscribers.

The alert calculation is based on the country_counts time series which stores alerts by country, hour and topics.

For each country and region, the process starts by aggregating the last N days. A day is a block of consecutive 24 hours ending before the hour of the collected last tweet. N is defined by the alert baseline parameter on the configuration tab of the Shiny application (the default is N=7).

An alert will be produced when the number of tweets observed is above the threshold calculated by the modified version of the EARS algorithm (for more details see the package vignette). The behaviour of the alert detection algorithm is modified by the signal false positive rate (alpha), downweighting of previous alerts and weekly or daily baseline parameters as defined on the configuration tab of the Shiny application and the topics file.

A prerequisite to this function is that the search_loop must already have stored collected tweets in the search folder and that the geotagging and aggregation tasks have already been run. Normally this function is not called directly by the user but from the detect_loop function.

Examples

Run this code

if(FALSE){
   library(epitweetr)
   # setting up the data folder
   message('Please choose the epitweetr data directory')
   setup_config(file.choose())

   # calculating alerts for last day tweets and sending emails to subscribers
   generate_alerts()
}