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Time-average a data table

time_average_dt.Rd

Aggregates meteorological data in a data table over specified time intervals. Handles flexible variable naming, wind direction vector averaging, and configurable reporting of interval start or end times. Uses openair::timeAverage() for aggregation with support for custom statistics (mean, median, sum, etc.).

Usage

time_average_dt(
  dt_in,
  avg.time = "30 min",
  statistic = "mean",
  first_date = NULL,
  last_date = NULL,
  time_name = NULL,
  wd_name = NULL,
  ws_name = NULL,
  report_end_interval = TRUE,
  extra_rows = 2
)

Arguments

dt_in

A data table containing meteorological observations with a time column.

avg.time

Time interval for averaging (e.g., "30 min", "1 hour"). Default: "30 min". Passed to openair::timeAverage().

statistic

Character string specifying the aggregation statistic ("mean", "median", "sum", etc.). Default: "mean". Use "median" for quality control codes.

first_date

Optional POSIXct date. Earliest date to include. If NULL, uses minimum date in data.

last_date

Optional POSIXct date. Latest date to include. If NULL, uses maximum date in data.

time_name

Character string. Name of the time column in dt_in (e.g., "time").

wd_name

Character string. Name of wind direction column, if present. Used for vector averaging.

ws_name

Character string. Name of wind speed column, if present. Used for vector averaging.

report_end_interval

Logical. If TRUE (default), timestamps report the end of the averaging interval. If FALSE, timestamps report the start of the interval (default openair behavior).

extra_rows

Integer (default: 2). Number of extra time intervals to include before and after the specified date range, used for padding during averaging.

Value

A data table with time-averaged values, preserving the original time column name and variable structure. The "site" column is stored as character.

Details

- Creates a temporary copy of input data to avoid modifying the original by reference. - Renames the time column to "date" for compatibility with openair::timeAverage(). - Optionally renames wind direction and wind speed columns for proper vector averaging. - Pads the averaging window with extra intervals (controlled by extra_rows) then restricts results to the original date range. - Converts any factor columns (e.g., "site") to character for consistency. - Uses "nocb" (next observation carried backward) to fill leading missing values. - Restores original time and column names in the output.

See also

- time_average for averaging a `metamet` object - add_era5 for applying time averaging to ERA5 reference data

Examples

# dt_averaged <- time_average_dt(
#   dt_in = my_dt,
#   avg.time = "1 hour",
#   time_name = "time",
#   wd_name = "wind_direction",
#   ws_name = "wind_speed"
# )