add_date_variables: Add year, month, and day of year variable columns to daily...

In fasstr: Analyze, Summarize, and Visualize Daily Streamflow Data

Add year, month, and day of year variable columns to daily flows

Description

Add columns of CalendarYear (YYYY), Month (MM), MonthName (e.g. 'Jan'), WaterYear (YYYY), and DayofYear (1-365 or 366; of WaterYear); to a data frame with a column of dates called 'Date'. Water years are designated by the year in which they end. For example, Water Year 1999 (starting Oct) is from 1 Oct 1998 (DayofYear 1) to 30 Sep 1999 (DayofYear 365)).

Usage

add_date_variables(data, dates = Date, station_number, water_year_start = 1)

Arguments

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 NULL 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 or set to NULL 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.
water_year_start	Numeric value indicating the month (1 through 12) of the start of water year for analysis. Default 1.

Value

A tibble data frame of the source data with additional columns:

CalendarYear	calendar year
Month	numeric month (1 to 12)
MonthName	month abbreviation (Jan-Dec)
WaterYear	year starting from the selected month start, water_year_start
DayofYear	day of the year from the selected month start (1-365 or 366)

Examples

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

# Add date variables using calendar years
add_date_variables(station_number = "08NM116")

# Add date variables using water years starting in August
add_date_variables(station_number = "08NM116", 
                   water_year_start = 8)
                   
}

fasstr documentation built on Sept. 30, 2024, 9:24 a.m.