6. How raster functions map to stars functions

Sébastien Rochette, Adriano Fantini, Edzer Pebesma

star の vignette のより良いバージョンは、 https://r-spatial.github.io/stars/articles/ を参照。

[issue #122] (https://github.com/r-spatial/stars/issues/122) で説明した raster の関数が stars の関数にどのように対応するかを説明する表の試みが、ここにある。この表は raster パッケージの関数をテンプレートとして使用している。不完全、不正確、あるいは明らかに間違っているだろうので、塩の一つまみをもって見てみよう。どんなコメントや修正も大歓迎である。

一部の関数( filter , slice , mutate , select , pull , … )は dplyr を介して提供されており、これを読み込む必要がある。?stars::dplyr を参照。

comment legend

よくわからない／不明

* ⑭不在、低優先度

# ⑭不在、高優先度

NA = デザイン上、利用できない

オブジェクトの作成

raster stars Note/comment
{raster, stack, brick} (read) read_stars or read_stars(along = …)
{stack, brick} (concatenate layers) c or c(along = …)
subset {[ ] , slice, filter}
addLayer c() or c(along = …)
dropLayer {[ ] , slice, filter}
unstack combine lapply and {[ ] , slice, filter}

物体の空間的な広がりや解像度を変更する

raster stars Note/comment
merge c #, currently only works for adjacent objects
mosaic st_mosaic these are not identical, read the docs carefully
crop filter, st_crop
setExtent # maybe use st_warp?
trim #
aggregate aggregate WIP; raster’s aggregate with fact=2 will not work, use st_warp in that case?
disaggregate # use st_warp(use_gdal = TRUE)?
resample {st_transform, st_warp}
projectRaster {st_transform, st_warp}
shift #, now use st_set_dimensions
flip [] with reversed index #
rotate *
t NA

セルベースコンピューティング

raster stars Note/comment
calc st_apply
overlay c(along = , …) %>% st_apply(…)
cover [ ] <-
mask [ ], st_crop when using an sf polygon as mask
mask [ ]<- NA when using a stars object to mask
cut cut
subs
reclassify mutate with case_when or forcats::fct_recode ?
reclassify cut see https://stackoverflow.com/questions/70619002/reclassify-2d-stars-array/
init [ ] <-
stackApply {[ ] , slice, filter} %>% st_apply
stackSelect

空間的な文脈の計算

raster stars Note/comment
distance #
gridDistance *
distanceFromPoints #
direction *
focal f = st_apply(x1, 3, foc, w = matrix(1, 3, 3)) See. issue 176
localFun *
boundaries st_as_sf(as_points=FALSE, merge=TRUE, connect8=TRUE)
clump st_as_sf(r, merge = TRUE) st_as_sf returns polygons, clump a raster
adjacent *
area st_area
terrain #
Moran

モデル予測

raster stars Note/comment
predict predict
interpolate gstat::idw, gstat::krige st_warp has raster-raster interpolations of gdalwarp

データ型変換

raster stars Note/comment
rasterize st_as_stars
rasterToPoints st_as_sf(as_points=TRUE)
rasterToPolygons st_as_sf(as_points=FALSE, …), st_polygonize
rasterToContour st_contour requires GDAL >= 2.4.0
rasterFromXYZ
rasterFromCells

まとめる

raster stars Note/comment
cellStats st_apply
summary print, summary(as.vector(. %>% pull))
freq table *
crosstab
unique unique(as.vector(. %>% pull))
zonal *

オブジェクトの値にアクセスする

raster stars Note/comment
getValues {pull, [[ ]]}
getValuesBlock {[ ] , slice, filter} %>% pull
getValuesFocal {[ ] , slice, filter} %>% pull
as.matrix [[ ]] currently behaves somewhat unexpectedly *
as.array [[ ]] currently behaves somewhat unexpectedly *
extract (by cell) {[ ] , slice, filter}
extract (by polygon) x[sf_object]
extract (by point) aggregate(stars_object, sf_object, function(x) x[1], as_points = FALSE)
sampleRandom *
sampleRegular *
minValue purrr::map(x, min)
maxValue purrr::map(x, max)
setMinMax ,

プロット

raster stars Note/comment
plot plot, geom_stars
plotRGB plot(x, rgb =…)
spplot -
image image
persp -
contour (st_contour, then sf::plot)
filledContour (same)
text text
hist hist(x[[1]])
barplot
density
pairs
boxplot

ディメンジョンの取得と設定

raster stars Note/comment
ncol dim(x)[1] or use name instead of 1; cols may be the second dimension!
nrow dim(x)[2] or use name instead of 2; rows may be the first dimension!
ncell prod(dim(x))
res st_dimensions can also not be a constant in case of rectilinear or curvilinear grids
nlayers - there is no concept of layers in stars
names names
xres st_res(x)[1] may not be a constant in case of rectilinear or curvilinear grids
yres st_res(x)[2] may not be a constant in case of rectilinear or curvilinear grids
xmin st_bbox(x)[1]
xmax st_bbox(x)[3]
ymin st_bbox(x)[2]
ymax st_bbox(x)[4]
extent st_bbox(x) different ordering of numbers
origin -
projection st_crs(x)
isLonLat st_is_longlat(st_crs(x))
filename stars_proxy objects carry file names where otherwise the array data is
bandnr stars has no general concept of bands
nbands dim(x)[3] may also be time; bands may also be in another dimension, or have another name
compareRaster all.equal(st_dimensions(x), st_dimensions(y)) *
NAvalue -

行、列、セルの番号と座標を計算する

raster stars Note/comment
xFromCol st_get_dimension_values(., ‘x’)[col] I am not sure how to generally get the x dimension name - here it is x
yFromRow st_get_dimension_values(., ‘y’)[row] I am not sure how to generally get the y dimension name - here it is y
xFromCell
yFromCell
xyFromCell
colFromX *
rowFromY *
rowColFromCell
cellFromXY st_cells()
cellFromRowCol
cellsFromExtent
coordinates st_coordinates
validCell
validCol col %>% between(st_dimensions(.)\(x\)from, st_dimensions(.)\(x\)to) raster columns are not always named ‘x’
validRow row %>% between(st_dimensions(.)\(y\)from, st_dimensions(.)\(y\)to) raster columns are not always named ‘y’
setValues [ ] <-
writeRaster write_stars currently uses GDAL, somewhat limited
KML

この表のフォーマットは、ラスタマニュアルの raster-package の項目 ( https://cran.r-project.org/web/packages/raster/raster.pdf ) に従っている。