我需要帮助阅读多个netCDF文件,尽管这里有一些例子,但它们都不能正常工作。 我使用Python(x,y)版本2.7.5和其他软件包:netcdf4 1.0.7-4,matplotlib 1.3.1-4,numpy 1.8,pandas 0.12,basemap 1.0.2...
我用GrADS做了很多事情,现在需要开始用Python做。 我有一些2米温度数据(来自ECMWF的每年4小时数据),每个文件包含2米温度数据,Xsize=480,Ysize=241, Zsize(水平)=1,Tsize(时间)=1460或闰年的1464。 这些是我的文件名类似于:t2m.1981.nc,t2m.1982.nc,t2m.1983.nc ...等。
根据这个页面: (Loop through netcdf files and run calculations - Python or R) 这是我目前的进展:
from pylab import *
import netCDF4 as nc
from netCDF4 import *
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap
import numpy as np
f = nc.MFDataset('d:/data/ecmwf/t2m.????.nc') # as '????' being the years
t2mtr = f.variables['t2m']
ntimes, ny, nx = shape(t2mtr)
temp2m = zeros((ny,nx),dtype=float64)
print ntimes
for i in xrange(ntimes):
temp2m += t2mtr[i,:,:] #I'm not sure how to slice this, just wanted to get the 00Z values.
# is it possible to assign to a new array,...
#... (for eg.) the average values of 00z for January only from 1981-2000?
#creating a NetCDF file
nco = nc.Dataset('d:/data/ecmwf/t2m.00zJan.nc','w',clobber=True)
nco.createDimension('x',nx)
nco.createDimension('y',ny)
temp2m_v = nco.createVariable('t2m', 'i4', ( 'y', 'x'))
temp2m_v.units='Kelvin'
temp2m_v.long_name='2 meter Temperature'
temp2m_v.grid_mapping = 'Lambert_Conformal' # can it be something else or ..
#... eliminated?).This is straight from the solution on that webpage.
lono = nco.createVariable('longitude','f8')
lato = nco.createVariable('latitude','f8')
xo = nco.createVariable('x','f4',('x')) #not sure if this is important
yo = nco.createVariable('y','f4',('y')) #not sure if this is important
lco = nco.createVariable('Lambert_Conformal','i4') #not sure
#copy all the variable attributes from original file
for var in ['longitude','latitude']:
for att in f.variables[var].ncattrs():
setattr(nco.variables[var],att,getattr(f.variables[var],att))
# copy variable data for lon,lat,x and y
lono=f.variables['longitude'][:]
lato=f.variables['latitude'][:]
#xo[:]=f.variables['x']
#yo[:]=f.variables['y']
# write the temp at 2 m data
temp2m_v[:,:]=temp2m
# copy Global attributes from original file
for att in f.ncattrs():
setattr(nco,att,getattr(f,att))
nco.Conventions='CF-1.6' #not sure what is this.
nco.close()
#attempt to plot the 00zJan mean
file=nc.Dataset('d:/data/ecmwf/t2m.00zJan.nc','r')
t2mtr=file.variables['t2m'][:]
lon=file.variables['longitude'][:]
lat=file.variables['latitude'][:]
clevs=np.arange(0,500.,10.)
map = Basemap(projection='cyl',llcrnrlat=0.,urcrnrlat=10.,llcrnrlon=97.,urcrnrlon=110.,resolution='i')
x,y=map(*np.meshgrid(lon,lat))
cs = map.contourf(x,y,t2mtr,clevs,extend='both')
map.drawcoastlines()
map.drawcountries()
plt.plot(cs)
plt.show()
第一个问题出现在temp2m += t2mtr[1,:,:]
。我不确定如何切片数据以仅获取所有文件的00z(假设仅为1月份)。
其次,在运行测试时,cs = map.contourf(x,y,t2mtr,clevs,extend='both')
出现错误,提示“形状与z不匹配:找到(1,1),而不是(241,480)”。我知道输出数据上可能有一些错误,由于记录值时出现错误,但我无法弄清楚是什么/在哪里。
感谢您的时间。希望这不会让人困惑。