approx2: Smart linear NA interpolation

In berryFunctions: Function Collection Related to Plotting and Hydrology

Smart linear NA interpolation

Description

Smart interpolation: as approx, approx2 fills NAs in a vector with linear interpolation, but unlike approx, it can handle NAs at the ends of a vector (takes the first/last value available for those). Also, approx2 returns a vector only.

Usage

approx2(x, fill = NULL, n = length(x), quiet = FALSE, ...)

Arguments

x	Vector with (numeric) values
fill	Function to fill NAs at the start or end of the vector. See Details. DEFAULT: NULL
n	Number of points to interpolate to
quiet	Logical: suppress warning for no non-NA values? DEFAULT: FALSE
...	Further arguments passed to approx

Details

The function fill is used to fill missing values at the ends of the vector. It could be mean or median, for example, but must be a function that accepts na.rm=TRUE as an argument. The default (NULL) means to use the first (or last) observation available.

Value

Vector with NAs replaced with interpolation (not a list, as in approx!)

Author(s)

Berry Boessenkool, [e-mail], July 2015

See Also

approx, zoo::na.locf, ciBand for usage example

Examples

approx2(c(NA,NA))   # yields a message
approx2(c(NA,NA, 6, 4, 8, 9, 3, 2, 1)) # fills with first non-NA value
approx2(c( 2,NA, 6, 4, 8, 9, 3, 2, 1)) # interpolates linearly
approx2(c( 2, 4, 6, 4, 8, 9,NA, 2,NA)) # linear, then last non-NA at end

approx2(c(NA,NA, 6, 4, 8, 9, 3, 2, 1))
approx2(c(NA,NA, 6, 4, 8, 9, 3, 2, 1), fill=median) # first median, then linear
approx2(c(NA,NA, 6, 4, 8, 9, 3, 2, 1), fill=mean)

approx2(c( 3, 4, 6, 4, 8, 9,NA, 2,NA))
approx2(c( 3, 4, 6, 4, 8, 9,NA, 2,NA), fill=median)
approx2(c( 3, 4, 6, 4, 8, 9,NA, 2,NA), fill=mean)

approx2(c(NA,NA, 6, 4, 8, 9, 3, 2, 1), n=17)
approx2(c( 2,NA, 6, 4, 8, 9, 3, 2, 1), n=17)
approx2(c( 2, 4, 6, 4, 8, 9,NA, 2,NA), n=17)

berryFunctions documentation built on May 29, 2024, 4:01 a.m.