问题描述
我在R上还比较陌生.我正在尝试从netCDF文件中获取温度数据的不同点(纬度，经度)的时间序列.我的示例数据文件是此处和此处是小文件.我已经尝试过netCDF软件包和到目前为止使用的代码
I am relatively new on R.I am trying to get time series of different points ( lat, lon) of temperature data from a netCDF file.My sample data file is here and here is the small file . I have tried netCDF package and the code i have used so far
library(ncdf)
obsdata = open.ncdf("obs.nc")
print.ncdf(obsdata)
obsdatadates = obsdata$dim$time$vals
obsdatadates = as.Date(obsdatadates,origin = '1950-01-01')
obsdatadates
obsoutput = get.var.ncdf(obsdata, varid = 'tasmin', start = c(1,1,1),
count = c(1,1,22280))
dim(obsoutput)
datafinal=merge(obsdatadates,obsoutput)
任何人都可以帮助我获取时间序列的数据帧(第一列)以及针对该数据的特定点(纬度，经度)的另一个数据值.在这种情况下，我正在寻找特定纬度点(对于许多兴趣点重复)和给定变量(在这种情况下，数据为1950-01-01至2010-12-31的时间序列) tasmin).您的帮助将不胜感激.谢谢，似乎
Can anyone help me to get a dataframe of timeseries ( first column) and value of data in another for a particular points( lat, lon) of that data.In this case I am looking for time series ( 1950-01-01 to 2010-12-31 for which the data is ) for a particular lat lon point ( and repeat for many points of interests) and for given variable(in this case tasmin).Your help would be appreciated.Thank you,aseem
推荐答案
也许使用raster包，这不适用于所有NetCDF文件，但对您的文件适用:
Perhaps use the raster package, this won't work for all NetCDF files but it does for yours:
library(raster)
## brick reads all 22280 layers
r <- brick("obs.nc", varname = "tasmin")
## extract works for all time steps
vals <- extract(r, matrix(c(-120, 52.5), ncol = 2))
dim(vals)
## [1] 1 22280
请注意，它给出了一个1行，多列的矩阵，因为我只给extract()一个点.
Note that gives a 1-row, many column matrix because I only gave a single point to extract().
(提取很简单，可以从最近的像元直接复制，使用方法="bilinear"进行插值).有关其他选项，请参见?extract.
(The extraction is simple with direct copy from the nearest cell, use method = "bilinear" to do interpolation). See ?extract for other options.
这篇关于从R中的netCDF提取一个点的时间序列(lon，lat)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！