Amount of dry/wet days in a time series

Given a daily time series (usually precipitation), this function computes the average amount of wet/dry days in each month.

Usage

dwdays(x, ...)

# S3 method for default
dwdays(x, thr=0, type="wet", na.rm=TRUE, ... )

# S3 method for data.frame
dwdays(x, thr=0, type="wet", na.rm=TRUE, 
        dates=1, date.fmt="%Y-%m-%d", verbose=TRUE,...)

# S3 method for matrix
dwdays(x, thr=0, type="wet", na.rm=TRUE, 
        dates=1, date.fmt="%Y-%m-%d", verbose=TRUE,...)

Arguments

x

zoo, data.frame or matrix object, usually with daily time series of precipitation.
Measurements at several gauging stations can be stored in a data.frame of matrix object, and in that case, each column of x represent the time series measured in each gauging station, and the column names of x have to correspond to the ID of each station (starting by a letter).

thr

numeric. Value of daily precipitation used as threshold for classifying a day as dry/wet or not. Days with a precipitation value larger to thr are classified as wet days, whereas precipitation values lower to thr are classified as dry days.

type

character, indicating if the daily values have to be classified as dry or wet days. It works linked to the values specified in thr. Valid values are: wet, dry.

na.rm

Logical. Should missing values be removed before counting?

dates

numeric, factor or Date object indicating how to obtain the dates
If dates is a number (default), it indicates the index of the column in x that stores the dates
If dates is a factor, it is converted into Date class, using the date format specified by date.fmt
If dates is already of Date class, the code verifies that the number of days in dates be equal to the number of element in x

date.fmt

character indicating the format in which the dates are stored in dates, e.g. %Y-%m-%d. See format in as.Date.
ONLY required when class(dates)=="factor" or class(dates)=="numeric".

verbose

logical; if TRUE, progress messages are printed

...

further arguments passed to or from other methods.

Author

Mauricio Zambrano-Bigiarini, mzb.devel@gmail

Examples

## Loading the SanMartino precipitation data
data(SanMartinoPPts)
x <- SanMartinoPPts

## Average amount of wet days in each month (for this example, this means days 
## with precipitation larger than 0.1mm) 
dwdays(x, thr=0.1)