fasstr: add_date_variables – R documentation

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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)

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.
`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

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