fasstr (version 0.5.3)

add_date_variables: 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)

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)

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.

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)
                   
}