View source: R/calc_annual_normal_days.R
calc_annual_normal_days  R Documentation 
Calculates the number of days per year outside of the 'normal' range (typically between 25 and 75th percentiles) for each day of the year. Upper and lowerrange percentiles are calculated for each day of the year of from all years, and then each daily flow value for each year is compared. All days above or below the normal range are included. Analysis methodology is based on Environment and Climate Change Canada's Water Quantity indicator from the Canadian Environmental Sustainability Indicators. Calculates statistics from all values from complete years, unless specified. Returns a tibble with statistics.
calc_annual_normal_days(
data,
dates = Date,
values = Value,
groups = STATION_NUMBER,
station_number,
normal_percentiles = c(25, 75),
roll_days = 1,
roll_align = "right",
water_year_start = 1,
start_year,
end_year,
exclude_years,
months = 1:12,
transpose = FALSE
)
data 
Data frame of daily data that contains columns of dates, flow values, and (optional) groups (e.g. station numbers).
Leave blank or set to 
dates 
Name of column in 
values 
Name of column in 
groups 
Name of column in 
station_number 
Character string vector of seven digit Water Survey of Canada station numbers (e.g. 
normal_percentiles 
Numeric vector of two values, lower and upper percentiles, respectively indicating the limits of the
normal range. Default 
roll_days 
Numeric value of the number of days to apply a rolling mean. Default 
roll_align 
Character string identifying the direction of the rolling mean from the specified date, either by the first
( 
water_year_start 
Numeric value indicating the month ( 
start_year 
Numeric value of the first year to consider for analysis. Leave blank or set well before start date (i.e.

end_year 
Numeric value of the last year to consider for analysis. Leave blank or set well after end date (i.e.

exclude_years 
Numeric vector of years to exclude from analysis. Leave blank or set to 
months 
Numeric vector of months to include in analysis. For example, 
transpose 
Logical value indicating whether to transpose rows and columns of results. Default 
A tibble data frame with the following columns:
Year 
calendar or water year selected 
Below_Normal_Days 
number of days per year below the daily normal (default 25th percentile) 
Above_Normal_Days 
number of days per year above the daily normal (default 75th percentile) 
Days_Outside_Normal 
number of days per year below and above the daily normal (default 25/75th percentile) 
Transposing data creates a column of "Statistics" and subsequent columns for each year selected.
# Run if HYDAT database has been downloaded (using tidyhydat::download_hydat())
if (file.exists(tidyhydat::hy_downloaded_db())) {
# Calculate statistics with default limits of normal (25 and 75th percentiles)
calc_annual_normal_days(station_number = "08NM116")
# Calculate statistics with custom limits of normal
calc_annual_normal_days(station_number = "08NM116",
normal_percentiles = c(10,90),
start_year = 1980)
}
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