# summarize-generics: Summarize In terra: Spatial Data Analysis

 summarize R Documentation

## Summarize

### Description

Compute summary statistics for cells, either across layers or between layers (parallel summary).

The following summary methods are available for SpatRaster: `any, anyNA, all, allNA, max, min, mean, median, prod, range, stdev, sum, which.min, which.max`. See `modal` to compute the mode and `app` to compute summary statistics that are not included here.

Because generic functions are used, the method applied is chosen based on the first argument: "`x`". This means that if `r` is a SpatRaster, `mean(r, 5)` will work, but `mean(5, r)` will not work.

The `mean` method has an argument "trim" that is ignored.

If `pop=TRUE` `stdev` computes the population standard deviation, computed as:

`f <- function(x) sqrt(sum((x-mean(x))^2) / length(x))`

This is different than the sample standard deviation returned by `sd` (which uses `n-1` as denominator).

### Usage

```## S4 method for signature 'SpatRaster'
min(x, ..., na.rm=FALSE)

## S4 method for signature 'SpatRaster'
max(x, ..., na.rm=FALSE)

## S4 method for signature 'SpatRaster'
range(x, ..., na.rm=FALSE)

## S4 method for signature 'SpatRaster'
prod(x, ..., na.rm=FALSE)

## S4 method for signature 'SpatRaster'
sum(x, ..., na.rm=FALSE)

## S4 method for signature 'SpatRaster'
any(x, ..., na.rm=FALSE)

## S4 method for signature 'SpatRaster'
all(x, ..., na.rm=FALSE)

## S4 method for signature 'SpatRaster'
range(x, ..., na.rm=FALSE)

## S4 method for signature 'SpatRaster'
which.min(x)

## S4 method for signature 'SpatRaster'
which.max(x)

## S4 method for signature 'SpatRaster'
stdev(x, ..., pop=TRUE, na.rm=FALSE)

## S4 method for signature 'SpatRaster'
mean(x, ..., trim=NA, na.rm=FALSE)

## S4 method for signature 'SpatRaster'
median(x, na.rm=FALSE, ...)

## S4 method for signature 'SpatRaster'
anyNA(x)

## S4 method for signature 'SpatRaster'
noNA(x, FNA=FALSE)

## S4 method for signature 'SpatRaster'
allNA(x, FNA=FALSE)

```

### Arguments

 `x` SpatRaster `...` additional SpatRaster objects or numeric values; and arguments `filename`, `overwrite` and `wopt` as for `writeRaster` `na.rm` logical. If `TRUE`, `NA` values are ignored. If `FALSE`, `NA` is returned if `x` has any `NA` values `trim` ignored `pop` logical. If `TRUE`, the population standard deviation is computed. Otherwise the sample standard deviation is computed `FNA` logical. If `TRUE`, cells that would otherwise be `FALSE` are set to `NA`

### Value

SpatRaster

`app`, `Math-methods`, `modal`, `which.lyr`

### Examples

```set.seed(0)
r <- rast(nrows=10, ncols=10, nlyrs=3)
values(r) <- runif(ncell(r) * nlyr(r))

x <- mean(r)
# note how this returns one layer
x <- sum(c(r, r[]), 5)

# and this returns three layers
y <- sum(r, r[], 5)

max(r)
max(r, 0.5)

y <- stdev(r)
# not the same as
yy <- app(r, sd)

z <- stdev(r, r*2)

x <- mean(r, filename=paste0(tempfile(), ".tif"))
```

terra documentation built on Jan. 17, 2023, 5:18 p.m.