approximate uses the stats function approx to estimate values for cells that are NA by interpolation across layers. Layers are considered equidistant, unless argument z is used, or time(x) returns values that are not NA, in which case these values are used to determine distance between layers.

For estimation based on neighboring cells see focal

# S4 method for SpatRaster
approximate(x, method="linear", yleft, yright,
rule=1, f=0, ties=mean, z=NULL, NArule=1,filename="",  ...)

## Arguments

x

SpatRaster

method

specifies the interpolation method to be used. Choices are "linear" or "constant" (step function; see the example in approx

yleft

the value to be returned before a non-NA value is encountered. The default is defined by the value of rule given below

yright

the value to be returned after the last non-NA value is encountered. The default is defined by the value of rule given below

rule

an integer (of length 1 or 2) describing how interpolation is to take place at for the first and last cells (before or after any non-NA values are encountered). If rule is 1 then NAs are returned for such points and if it is 2, the value at the closest data extreme is used. Use, e.g., rule = 2:1, if the left and right side extrapolation should differ

f

for method = "constant" a number between 0 and 1 inclusive, indicating a compromise between left- and right-continuous step functions. If y0 and y1 are the values to the left and right of the point then the value is y0*(1-f)+y1*f so that f = 0) is right-continuous and f = 1 is left-continuous

ties

Handling of tied 'z' values. Either a function with a single vector argument returning a single number result or the string "ordered"

z

numeric vector to indicate the distance between layers (e.g., depth). The default is time(x) if these are not NA or else 1:nlys(x)

NArule

single integer used to determine what to do when only a single layer with a non-NA value is encountered (and linear interpolation is not possible). The default value of 1 indicates that all layers will get this value for that cell; all other values do not change the cell values

filename

character. Output filename

...

additional arguments for writing files as in writeRaster

## Value

SpatRaster

 focal, fillTime

## Examples

r <- rast(ncols=5, nrows=5)
r1 <- setValues(r, runif(ncell(r)))
r2 <- setValues(r, runif(ncell(r)))
r3 <- setValues(r, runif(ncell(r)))
r4 <- setValues(r, runif(ncell(r)))
r5 <- setValues(r, NA)
r6 <- setValues(r, runif(ncell(r)))
r1[6:10] <- NA
r2[5:15] <- NA
r3[8:25] <- NA
s <- c(r1,r2,r3,r4,r5,r6)
s[1:5] <- NA
x1 <- approximate(s)
x2 <- approximate(s, rule=2)
x3 <- approximate(s, rule=2, z=c(1,2,3,5,14,15))