fasstr: calc_annual_stats – R documentation

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calc_annual_stats

Calculate annual summary statistics

Description

Calculates means, medians, maximums, minimums, and percentiles for each year from all years of a daily streamflow data set. Calculates statistics from all values, unless specified. Returns a tibble with statistics.

Usage

calc_annual_stats(
  data,
  dates = Date,
  values = Value,
  groups = STATION_NUMBER,
  station_number,
  roll_days = 1,
  roll_align = "right",
  percentiles = c(10, 90),
  water_year_start = 1,
  start_year,
  end_year,
  exclude_years,
  months = 1:12,
  transpose = FALSE,
  ignore_missing = FALSE
)

Arguments

`data`	Data frame of daily data that contains columns of dates, flow values, and (optional) groups (e.g. station numbers). Leave blank if using `station_number` argument.
`dates`	Name of column in `data` that contains dates formatted YYYY-MM-DD. Only required if dates column name is not 'Date' (default). Leave blank if using `station_number` argument.
`values`	Name of column in `data` that contains numeric flow values, in units of cubic metres per second. Only required if values column name is not 'Value' (default). Leave blank if using `station_number` argument.
`groups`	Name of column in `data` that contains unique identifiers for different data sets, if applicable. Only required if groups column name is not 'STATION_NUMBER'. Function will automatically group by a column named 'STATION_NUMBER' if present. Remove the 'STATION_NUMBER' column beforehand to remove this grouping. Leave blank if using `station_number` argument.
`station_number`	Character string vector of seven digit Water Survey of Canada station numbers (e.g. `"08NM116"`) of which to extract daily streamflow data from a HYDAT database. Requires `tidyhydat` package and a HYDAT database. Leave blank if using `data` argument.
`roll_days`	Numeric value of the number of days to apply a rolling mean. Default `1`.
`roll_align`	Character string identifying the direction of the rolling mean from the specified date, either by the first (`'left'`), last (`'right'`), or middle (`'center'`) day of the rolling n-day group of observations. Default `'right'`.
`percentiles`	Numeric vector of percentiles to calculate. Set to `NA` if none required. Default `c(10,90)`.
`water_year_start`	Numeric value indicating the month (`1` through `12`) of the start of water year for analysis. Default `1`.
`start_year`	Numeric value of the first year to consider for analysis. Leave blank to use the first year of the source data.
`end_year`	Numeric value of the last year to consider for analysis. Leave blank to use the last year of the source data.
`exclude_years`	Numeric vector of years to exclude from analysis. Leave blank to include all years.
`months`	Numeric vector of months to include in analysis (e.g. `6:8` for Jun-Aug). Leave blank to summarize all months (default `1:12`).
`transpose`	Logical value indicating whether to transpose rows and columns of results. Default `FALSE`.
`ignore_missing`	Logical value indicating whether dates with missing values should be included in the calculation. If `TRUE` then a statistic will be calculated regardless of missing dates. If `FALSE` then only those statistics from time periods with no missing dates will be returned. Default `FALSE`.

Value

A tibble data frame with the following columns:

`Year`	calendar or water year selected
`Mean`	annual mean of all daily flows for a given year
`Median`	annual median of all daily flows for a given year
`Maximum`	annual maximum of all daily flows for a given year
`Minimum`	annual minimum of all daily flows for a given year
`P'n'`	each annual n-th percentile selected of all daily flows

Default percentile columns:

`P10`	annual 10th percentile of all daily flows for a given year
`P90`	annual 90th percentile of all daily flows for a given year

Transposing data creates a column of "Statistics" and subsequent columns for each year selected.

Examples

# Run if HYDAT database has been downloaded (using tidyhydat::download_hydat())
if (file.exists(tidyhydat::hy_downloaded_db())) {

# Calculate annual statistics from a data frame using the data argument
flow_data <- tidyhydat::hy_daily_flows(station_number = "08NM116")
calc_annual_stats(data = flow_data)

# Calculate annual statistics using station_number argument
calc_annual_stats(station_number = "08NM116")

# Calculate annual statistics regardless if there 
# is missing data for a given year
calc_annual_stats(station_number = "08NM116",
                  ignore_missing = TRUE)
                  
# Calculate annual statistics for water years starting in October
calc_annual_stats(station_number = "08NM116",
                  water_year_start = 10)
                  
# Calculate annual statistics filtered for custom years
calc_annual_stats(station_number = "08NM116",
                  start_year = 1981,
                  end_year = 2010,
                  exclude_years = c(1991,1993:1995))
                  
# Calculate annual statistics for 7-day flows for July-September 
# months only, with 25 and 75th percentiles
calc_annual_stats(station_number = "08NM116",
                  roll_days = 7,
                  months = 7:9,
                  percentiles = c(25,75))
                  
}

fasstr

Analyze, Summarize, and Visualize Daily Streamflow Data

v0.3.2

Apache License 2.0

Authors

Jon Goetz [aut, cre] (<https://orcid.org/0000-0002-4993-1119>), Carl James Schwarz [aut], Robin Pike [ctb], Province of British Columbia [cph]

Initial release