Question

我有一个光栅文件列表，我想浏览每个文件，如果有一个NA值，我想从列表中删除它！

喜欢这个列表

[1] "./2013105_33UXP_04_05_L8_sr_band2.tif" "./2013105_33UXP_04_05_L8_sr_band3.tif" "./2013105_33UXP_04_05_L8_sr_band4.tif"
  [4] "./2013105_33UXP_04_05_L8_sr_band5.tif" "./2013105_33UXP_04_05_L8_sr_band6.tif" "./2013105_33UXP_04_05_L8_sr_band7.tif"
  [7] "./2013114_33UXP_04_05_L8_sr_band2.tif" "./2013114_33UXP_04_05_L8_sr_band3.tif" "./2013114_33UXP_04_05_L8_sr_band4.tif"
 [10] "./2013114_33UXP_04_05_L8_sr_band5.tif" "./2013114_33UXP_04_05_L8_sr_band6.tif" "./2013114_33UXP_04_05_L8_sr_band7.tif"
 [13] "./2013121_33UXP_04_05_L8_sr_band2.tif" "./2013121_33UXP_04_05_L8_sr_band3.tif" "./2013121_33UXP_04_05_L8_sr_band4.tif"
 [16] "./2013121_33UXP_04_05_L8_sr_band5.tif" "./2013121_33UXP_04_05_L8_sr_band6.tif" "./2013121_33UXP_04_05_L8_sr_band7.tif"

我怎么做？

感谢

Answer 1

这是一个可重现的解决方案示例

library(raster)

# example data
r <- raster(ncol=10, nrow=10)

set.seed(0)
# 10 layers
s <- stack(lapply(1:10, function(i) setValues(r, runif(ncell(r)))))
# set about half the values to NA
s[s < .5] <- NA

s
#class       : RasterBrick 
#dimensions  : 10, 10, 100, 10  (nrow, ncol, ncell, nlayers)
#resolution  : 36, 18  (x, y)
#extent      : -180, 180, -90, 90  (xmin, xmax, ymin, ymax)
#coord. ref. : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0 
#data source : in memory
#names       :   layer.1,   layer.2,   layer.3,   layer.4,   layer.5,   layer.6,   layer.7,   layer.8,   layer.9,  layer.10 
#min values  : 0.5186343, 0.5004410, 0.5069395, 0.5070356, 0.5008505, 0.5253055, 0.5017548, 0.5161239, 0.5055311, 0.5019486 
#max values  : 0.9919061, 0.9926841, 0.9815635, 0.9960774, 0.9937492, 0.9959655, 0.9756573, 0.9994554, 0.9906600, 0.9999306

现在使用示例数据删除超过50％的NA

单元格的图层

# count the NA values in each layer
i <- cellStats(is.na(s), sum)
# fraction that is NA
i <- i/ncell(s)

i
# layer.1  layer.2  layer.3  layer.4  layer.5  layer.6  layer.7  layer.8  layer.9 layer.10 
#    0.52     0.46     0.62     0.56     0.53     0.44     0.46     0.51     0.55     0.54 

# select the layers that more than half the cells with values
ss <- s[[which(i>.5)]]

ss
#class       : RasterBrick 
#dimensions  : 10, 10, 100, 7  (nrow, ncol, ncell, nlayers)
#resolution  : 36, 18  (x, y)
#extent      : -180, 180, -90, 90  (xmin, xmax, ymin, ymax)
#coord. ref. : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0 
#data source : in memory
#names       :   layer.1,   layer.3,   layer.4,   layer.5,   layer.8,   layer.9,  layer.10 
#min values  : 0.5186343, 0.5069395, 0.5070356, 0.5008505, 0.5161239, 0.5055311, 0.5019486 
#max values  : 0.9919061, 0.9815635, 0.9960774, 0.9937492, 0.9994554, 0.9906600, 0.9999306

Answer 2

如果我们能够获得可重现的代码，显示当您将其中一个光栅文件读入R时的样子，那将会有所帮助。它是否作为数据框出现？作为清单？作为矩阵？这使得很难完全回答你的问题。

我想你会想要的东西......

library(dplyr)
library(raster)

new_list_of_files = list()

for (file in seq_along(list_of_files)){
     imported_raster = raster(file)
     df <- as.data.frame(imported_raster)

     #check NAs
     p_cent_na <- sum(is.na(df))/(nrow(df)*ncol(df))
     if (p_cent_na > .9){
            df[is.na(df),] <- 0
            new_list_of_files <- list(new_list_of_files, df)
     }
}

我不知道这是否有效，因为我需要一个你的.tif文件的例子。

从列表中删除具有NA值的光栅文件

2 个答案: