dr_drop: Dropping observations from the monitoring period

In driftR: Drift Correcting Water Quality Data

Description

dr_drop() includes three approaches for removing observations from the monitoring period. Observations may be removed by specifying the number to remove from the head and/or the tail of the observation. They may also be removed by specifying one or two timepoints in the data where problematic observations begin, end, or fall between. Finally observations may be removed based on a problematic sensor value or range of values using an expression.

Usage

dr_drop(.data, head = NULL, tail = NULL, dateVar = NULL, timeVar = NULL, from = NULL,
    to = NULL, tz = NULL, exp)

Arguments

.data	A tbl
head	An integer >= 1 specifying the number of rows to be removed from the top of .data (or NULL)
tail	An integer >= 1 specifying the number of rows to be removed from the bottom of .data (or NULL)
dateVar	Name of variable containing date data
timeVar	Name of variable containing time data
from	Beginning date and (optionally) time to remove observations
to	End date and (optionally) time to remove observations
tz	String name of timezone, defaults to system's timezone
exp	Unquoted expression

Details

When taking the instrument out of the water, there are often several observations that pass before the run can be downloaded. Additionally, once the instrument is in the water, it often takes about 30 minutes for the sensors to equilibrate. This function allows you to drop observations from the bottom and top of the data set for each of those issues respectively. This function also provides approaches for removing observations from the middle of the data set.

Value

An object of the same class as .data with specified observations removed.

Examples

testData <- data.frame(
   Date = c("9/18/2015", "9/18/2015", "9/18/2015", "9/18/2015", "9/19/2015", "9/21/2015"),
   Time = c("12:10:49", "12:15:50", "12:20:51", "12:25:51", "12:30:51", "12:35:51"),
   Temp = c(14.76, 14.64, 14.57, 14.51, 14.50, 14.63),
   SpCond = c(0.754, 0.750, 0.750, 0.749, 0.749, 0.749),
   stringsAsFactors = FALSE
 )

 dr_drop(testData, head = 2)
 dr_drop(testData, tail = 1)
 dr_drop(testData, head = 2, tail = 1)
 dr_drop(testData, dateVar = Date, timeVar = Time, from = "9/19/2015")
 dr_drop(testData, dateVar = Date, timeVar = Time, from = "9/18/2015 12:25:51")
 dr_drop(testData, dateVar = Date, timeVar = Time, to = "9/19/2015")
 dr_drop(testData, dateVar = Date, timeVar = Time, to = "9/18/2015 12:25:51")
 dr_drop(testData, dateVar = Date, timeVar = Time, from = "9/18/2015 12:25:51",
     to = "9/19/2015 12:30:51")
 dr_drop(testData, dateVar = Date, timeVar = Time, from = "9/18/2015 12:00", to = "9/19/2015 13:00")
 dr_drop(testData, exp = Temp > 14.7)

driftR documentation built on May 1, 2019, 8:43 p.m.