错误绘制来自netcdf文件的数据“期望增加x y值" [英] Error plotting data from netcdf file "increasing x y values expected"

问题描述

我想从规则的网格中绘制海面温度数据，但找不到正确的方法.我的数据为nc格式 可以从 http://www.nodc.noaa.gov/SatelliteData/pathfinder4km/<下载/a>

I want to plot sea surface temperature data from a regular grid but can't find the proper way to do it. My data comes in nc format and can be downloaded from http://www.nodc.noaa.gov/SatelliteData/pathfinder4km/

我使用此R代码访问数据，但是在尝试绘制时出现了问题

I use this R code to access data but the problem appears when trying to plot

library("ncdf")
download.file("ftp://ftp.nodc.noaa.gov/pub/data.nodc/pathfinder/Version5.2/2003/20030715000715-NODC-L3C_GHRSST-SSTskin-AVHRR_Pathfinder-PFV5.2_NOAA17_G_2003196_night-v02.0-fv02.0.nc", destfile="sst.nc")
data=open.ncdf("sst.nc")
x <- get.var.ncdf(data,"lon")
y <- get.var.ncdf(data,"lat")
sst=get.var.ncdf(data,"sea_surface_temperature")

filled.contour(x,y,sst, color = terrain.colors, asp = 1)

然后收到此错误消息

filled.contour(x，y，sst，color = terrain.colors，asp = 1)错误: 预期增加"x"和"y"值

Error en filled.contour(x, y, sst, color = terrain.colors, asp = 1) : increasing 'x' and 'y' values expected

我认为问题出在y坐标，纬度从90到-90.我已经在使用akima创建新网格时看到了一些关于stackoverflow的问题 包，但在这种情况下不必要.

I think the problem comes from y coordinate, latitude runs from 90 to -90. I've seen some questions on stackoverflow in creating a new grid with akima package but it should not be necessary in this case.

在这里您可以找到数据文件的摘要

Here you can find a summary of data file

http://ubuntuone.com/1mIdYVqoePn24gKQbtXy7K

预先感谢您的帮助

已解决

感谢Paul Hiemstra

Thanks to Paul Hiemstra

该点不是从数据集中读取纬度值，而是要知道矩阵中数据点的i，j坐标，然后选择要绘制的地理区域.以下是对我有用的命令:

The point was not read lat-lon values from data set but to know the i,j coordinates of data points in the matrix and then select the geographic area I want to plot. Following are the commands that work for me:

library("ncdf")
download.file("ftp://ftp.nodc.noaa.gov/pub/data.nodc/pathfinder/Version5.2/2003/20030715000715-NODC-L3C_GHRSST-SSTskin-AVHRR_Pathfinder-PFV5.2_NOAA17_G_2003196_night-v02.0-fv02.0.nc", destfile="sst.nc")
data=open.ncdf("sst.nc")
sst=get.var.ncdf(data,"sea_surface_temperature")
x = seq(1, 8640, length.out = nrow(sst))         # Matrix dimension 8640x4320
y = seq(1, 4320, length.out = ncol(sst))

sst1 <- sst[c(1000:1500),c(1000:1500)]           # Subsetting a region
x = seq(1, 500, length.out = nrow(sst1))
y = seq(1, 500, length.out = ncol(sst1))

png(filename="sst.png",width=800,height=600,bg="white")
filled.contour(x,y,sst1, color = terrain.colors, asp = 1)
dev.off()

现在，我必须弄清楚如何在x-y坐标处以经度和纬度标记图.

Now I have to figure out how to label the plot with longtiude and latitude at x-y coordinates.

推荐答案

问题可能出在下面.您的x和y变量的大小与sst相同，即它们提供了x和y坐标的映射. filled_contour函数所需的不是这些映射，而是更简单的x和y坐标，它们与sst中的行和列关联，且x值增加.

The problem is probably the following. Your x and y variables are of the same size of sst, i.e. they provide maps of x and y coordinates. What the filled_contour function needs is not these maps, but more simply the x and y coordinates associated with the rows and columns in sst with increasing x values.

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