英文:
Subsetting a RasterBrick based on values in a RasterLayer
问题
我有一个包含172个图层的 RasterBrick（每个图层对应不同的时间步），我们可以称之为 m。
对于 m 的每个单元格，我想保留只大于所有图层的平均值的值（每个单元格有一个平均值）。然后，我想计算这个新的“筛选” RasterBrick 的平均值。
我计算了一个 RasterLayer，其中包含 m 的每个单元格的平均值：
mean_m <- mean(m, na.rm = TRUE)
然后执行了：
c <- m > mean_m
但是得到的是一个包含布尔值（0或1）的 RasterBrick。然后我尝试执行：
m[[c]]
但它仍然没有起作用。
是否有一种在 R 中使用 Raster 格式轻松完成此操作的方法？我知道我可以将 Raster* 文件转换为数据框，但我相信使用 Raster* 将极大加快我的工作流程。
非常感谢您的帮助！
英文:
I have one RasterBrick with 172 layers (every layer corresponds to a different time step), that we can call m.
For every cell of m, I would like to keep only the values that are bigger than the mean across all layers (one mean value per cell). Then, I would like to calculate the mean of this new "filtered" RasterBrick.
I calculated a RasterLayer with the mean value of each cell of m:
mean_m <- mean(m, na.rm = TRUE)
And then did:
c <- m > mean_m
But what I get is a RasterBrick of boolean values (0 or 1). I then tried to do:
m[[c]]
It still didn't work.
Is there an easy way of doing this using the Raster format on R? I know that I could convert the Raster* files to dataframes, but I believe working with Raster* would speed up my workflow tremendously.
Thanks a lot in advance for your help!
答案1
得分: 0
以下是您要翻译的内容：
You can use "terra" for that (the replacement of "raster")
Example data
```R
library(terra)
s <- rast(system.file("ex/logo.tif", package="terra"))
Solution
m <- mean(s)
x <- ifel(s > m, s, NA)
res <- mean(x, na.rm=TRUE)
You can also do
res2 <- app(s, \(x) mean(x[x > mean(x)]))
<details>
<summary>英文:</summary>
You can use "terra" for that (the replacement of "raster")
Example data
library(terra)
s <- rast(system.file("ex/logo.tif", package="terra"))
Solution
m <- mean(s)
x <- ifel(s > m, s, NA)
res <- mean(x, na.rm=TRUE)
You can also do
res2 <- app(s, (x) mean(x[x > mean(x)]))
</details>
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