Combine observed data with a single prediction draw

Internally it sums observed counts from the reporting triangle by reference time and adds them to the predicted counts to form a single draw of the nowcast for the final counts by reference time.

Usage

combine_obs_with_pred(
  predicted_counts,
  reporting_triangle,
  fun_to_aggregate = sum,
  k = 1
)

Arguments

predicted_counts

Vector of predicted counts at each reference time

reporting_triangle

Matrix of the reporting triangle, with rows representing the time points of reference and columns representing the delays. Can be a reporting matrix or incomplete reporting matrix. Can also be a ragged reporting triangle, where multiple columns are reported for the same row. (e.g. weekly reporting of daily data).

fun_to_aggregate

Function that will operate along the nowcast vectors after summing across delays. Eventually, we can add things like mean, but for now since we are only providing a negative binomial observation model, we can only allow sum. Currently supported functions: sum.

k

Integer indicating the number of reference times to apply the fun_to_aggregate over to create target used to compute the nowcast errors.

Value

A vector of predicted counts at each reference time

Examples

pred_counts <- c(10, 20, 30, 40)
reporting_matrix <- matrix(
  c(
    1, 2, 3, 4,
    5, 6, 7, 8,
    9, 10, 11, 12
  ),
  nrow = 4,
  byrow = TRUE
)
reporting_triangle <- generate_triangle(reporting_matrix)
combine_obs_with_pred(pred_counts, reporting_triangle)
#> [1] 16 35 45 50