按月细分栅格砖

如何解决按月细分栅格砖

我给自己找到了一个名为y的栅格砖，该栅格具有14 975个时间层，因为它具有从1979年1月1日到2019年12月31日（14 975天）的每日平均平均地势高的值。砖块具有以下描述：

class      : RasterBrick 
dimensions : 221,121,26741,14975  (nrow,ncol,ncell,nlayers)
resolution : 0.25,0.25  (x,y)
extent     : 14.875,45.125,24.875,80.125  (xmin,xmax,ymin,ymax)
crs        : +proj=longlat +datum=WGS84 
source     : C:/Users/Adam/AppData/Local/Temp/RtmpaKZVdb/raster/r_tmp_2020-10-26_165849_53084_29346.grd 
names      : index_1979.01.01,index_1979.01.02,index_1979.01.03,index_1979.01.04,index_1979.01.05,index_1979.01.06,index_1979.01.07,index_1979.01.08,index_1979.01.09,index_1979.01.10,index_1979.01.11,index_1979.01.12,index_1979.01.13,index_1979.01.14,index_1979.01.15,... 
min values :         46604.85,47328.07,48944.12,49320.65,49244.67,49516.16,49504.01,48959.65,48608.90,47603.10,47572.72,48564.15,49816.92,49078.65,48321.72,... 
max values :         57006.81,56968.60,56958.67,56976.26,57288.55,57535.62,57659.48,57581.33,57381.65,57052.99,56803.95,56854.89,56783.50,56739.44,56600.52,... 

，我想按月将这个栅格砖细分为12个栅格砖，以便每个日历月有1个栅格砖。我尝试了几种方法，但是效果不佳。例如，我试图从名称（y）中减去月份字符，但我认为这肯定是可行的方法，但根本行不通。每一个帮助表示感谢，谢谢！

解决方法

如果您尝试这样做：

# We changed the names of the layers to months:

layer_names_original <- names(y)
layer_names <- layer_names_original

layer_names_2 <- gsub('index_','',layer_names)
layer_names_3 <- gsub('\\.','-',layer_names_2)
layer_names_3_as_date <- as.Date(layer_names_3)

library(lubridate)
layer_names_3_in_months <- month(layer_names_3_as_date)
names(y) <- layer_names_3_in_months

# We filtered the layers of the month 'i'
i <- 1 # january
y_i <- y[[i]] 

# We replaced the month names by the originals
id_match <- which(names(y)%in%i)
names(y_i) <- layer_names_original[id_match]


# Pd: Try changed brick by stack in case of problems (y <- stack(y))

,

您可以尝试以下方法：

layer_names <- names(y)
layer_names_2 <- gsub('index_',layer_names_2)
layer_names_3_as_date <- as.Date(layer_names_3)

library(lubridate)
layer_names_3_in_months <- month(layer_names_3_as_date)

# We filtered the layers of the month 'i'
i <- 1 # january
layer_names_3_in_months_i <- which(layer_names_3_in_months==i) 
layer_month_i <- names(y)[layer_names_3_in_months_i]

# Filter done
y[[layer_month_i]]

# Pd: Try changed brick by stack in case of problems (y <- stack(y))