用正确的网格在R中绘制netcdf [英] Plotting netcdf in R with correct grid
问题描述
我的目标是在世界地图上绘制硝酸盐(no3)数据,使用这些数据的正确经度和纬度。
有两个netcdf文件:
1. 与数据 a>
2.使用网格信息 p>
数据摘要信息:
no3是长度为x * y * sigma
的数组no3_df是'x * y obs。 3个变量'
x = integer [180]
y = integer [193]
sigma = array [53]
我想看看sigma('depth')20.因此,我做了以下操作:
#加载所需的库来处理netcdf文件
library(ncdf)
library(akima)
#打开数据和网格文件
file1< - open.ncdf(file.choose())
grid< - open.ncdf(file.choose())
#从数据文件1读取相关变量/参数
x< - get.var.ncdf(file1,varid = (file1,varid =y)
sigma< - get.var.ncdf(file1,varid =sigma)
no3 < - get.var.ncdf(file1,varid =no3)
sigma_plot < - no3 [,, sigma = 20]
#从网格中读取相关变量/参数文件
plon< - get.var.ncdf(grid,varid =plon)
plat< - get.var.ncdf(grid,varid =plat)
#sigma_plot的每个单元格对应于plon和plat的一个单元格。
A< - array(c(plon,plat,sigma_plot),dim = c(180,193,3))
#现在B是一个包含每行的数组:(经度,纬度,价值)。
B < - apply(A,3,cbind)
#但它不是一个正常的网格,所以插入一个规则的网格。 akima库
C < - interp(B [,1],B [,2],B [,3],
xo = seq(-180,180,1),yo = seq(-90 ,90,by = 1),#在这里调整分辨率
duplicate ='mean')#额外的y值是重复的
#########
#绘制
#########
#这一个可行,但没有正确的经度和纬度:
filled.contour(x,y ,sigma_plot,col = rich.colors(18))
#尝试用lon和lat
填充fill.contour(C,col = rich.colors(30))
由于filled.contour绘图没有正确的经度和纬度,我想使用ggplot。但是,我不知道该怎么做......
#和ggplot一起绘制
ggplot( aes(x = plon_datafrm,y = plat_datafrm),data = no3_df)+
geom_raster()+
coord_equal()+
scale_fill_gradient()
这似乎不起作用。我是ggplot的网络,所以这可能是原因,我真的很感谢任何帮助。
data < - open.ncdf(file1)
no3 < - get.var.ncdf(data,varid =no3)
sigma_plot< - no3 [,, 20]
grid< - open.ncdf(file2)
plon< - get.var.ncdf(grid,varid =plon)
plat< - get.var.ncdf(grid,varid =plat)
与我以前的理解相反,sigma_plot的每个单元对应于plon和plat的一个单元。
A < - array(c(plon,plat, a),dim = c(180,193,3))
B < - apply(A,3,cbind)
现在B是包含每行的数组:(经度,纬度,值)。但它不是一个规则的网格,所以你需要插入一个规则的网格。最简单的方法是使用 akima
interp (akima)
C < - interp(B [,1],B [,2],B [,3],
xo = seq( -180,180,1),yo = seq(-90,90,by = 1),#你可以在这里调整分辨率
duplicate ='mean')#由于某些原因某些条目是重复的,我不知道你想如何处理它。
image(C)#例如,如果您偏好
library(maptools)
data(wrld_simpl)
plot(wrld_simpl,add = TRUE ,col =white)#在上面添加一个简单的世界地图
My goal is to plot nitrate (no3) data on a world map, using the correct longitude and latitude for these data.
There are two netcdf files:
1. with the data
2. with the grid information
Summary info on the data: no3 is an array of length x*y*sigma no3_df is 'x*y obs. of 3 variables' x = integer [180] y = integer [193] sigma = array[53]
I want to look at sigma ('depth') 20. I therefore did the following:
# Load the needed libraries to handle netcdf files
library(ncdf)
library(akima)
# Open data and grid files
file1 <- open.ncdf(file.choose())
grid <- open.ncdf(file.choose())
# Read relevant variables/parameters from data file1
x <- get.var.ncdf(file1,varid="x")
y <- get.var.ncdf(file1,varid="y")
sigma <- get.var.ncdf(file1,varid="sigma")
no3 <- get.var.ncdf(file1,varid="no3")
sigma_plot <- no3[,,sigma=20]
# Read relevant variables/parameters from grid file
plon <- get.var.ncdf(grid,varid="plon")
plat <- get.var.ncdf(grid,varid="plat")
# Each cell of sigma_plot corresponds to one cell of plon and plat.
A <- array(c(plon,plat,sigma_plot),dim=c(180,193,3))
# Now B is an array containing for each row: (longitude, latitude, value).
B <- apply(A, 3, cbind)
# But it is not a regular grid, so interpolate to a regular grid. akima library
C <- interp(B[,1],B[,2],B[,3],
xo=seq(-180,180,1),yo=seq(-90,90,by=1), # tweak here the resolution
duplicate='mean') # extra y values are duplicates
#########
# PLOTTING
#########
# This one works, but doesn't have a correct longitude and latitude:
filled.contour(x,y,sigma_plot, col=rich.colors(18))
# Try to plot with lon and lat
filled.contour(C, col=rich.colors(30))
Since the filled.contour plot doesn't have correct longitude and latitude, I would like to use ggplot. However, I don't know how to do this...
# And the plotting with ggplot
ggplot(aes(x=plon_datafrm,y=plat_datafrm),data=no3_df) +
geom_raster() +
coord_equal() +
scale_fill_gradient()
This doesn't seem to work. I am net to ggplot so that might be the reason, I would truly appreciate any help.
library(ncdf)
data <- open.ncdf(file1)
no3 <- get.var.ncdf(data,varid="no3")
sigma_plot <- no3[,,20]
grid <- open.ncdf(file2)
plon <- get.var.ncdf(grid,varid="plon")
plat <- get.var.ncdf(grid,varid="plat")
Contrary to what I previously understood, each cell of sigma_plot corresponds to one cell of plon and plat.
A <- array(c(plon,plat,a),dim=c(180,193,3))
B <- apply(A, 3, cbind)
Now B is an array containing for each row: (longitude, latitude, value). But it is not a regular grid, so you need to interpolate a regular grid. Easiest way would be using interp
from package akima
:
library(akima)
C <- interp(B[,1],B[,2],B[,3],
xo=seq(-180,180,1),yo=seq(-90,90,by=1), #you can tweak here the resolution
duplicate='mean') #for some reasons some entries are duplicates, i don t know how you want to handle it.
image(C) #for instance, or filled.contour if you prefer
library(maptools)
data(wrld_simpl)
plot(wrld_simpl, add=TRUE, col="white") #To add a simple world map on top
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