MeteoInfoLab脚本示例：GrADS转netCDF

MeteoInfo · 发表于 2016-4-15 16:27:00

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本帖最后由 MeteoInfo 于 2017-4-3 11:11 编辑

convert2nc(infn, outfn)函数用来将GrADS数据转为netCDF格式数据（目前只支持等经纬度投影数据），第一个参数为欲转换的GrADS数据文件名，第二个参数为转换后的netCDF数据文件名。

脚本程序：

infn = 'D:/Temp/grads/model.ctl' #Input GrADS file
outfn = 'D:/Temp/grads/model.nc' #Output netCDF file
convert2nc(infn, outfn)

也可以不用convert2nc函数，更加灵活的转换：

#--------------------------------------------------------
# Author: Yaqiang Wang
# Date: 2016-4-12
# Purpose: Convert GrADS data to netCDF data
# Note: Sample
#-----------------------------------------------------------
infn = 'D:/Temp/grads/model.ctl' #Input GrADS file
outfn = 'D:/Temp/grads/model.nc' #Output netCDF file
#Open GrADS file
f = addfile(infn)
#New netCDF file
ncfile = addfile(outfn, 'c')
#Add dimensions
dims = []
for dim in f.dimensions():
dims.append(ncfile.adddim(dim.getShortName(), dim.getLength()))
xdim = f.finddim('X')
ydim = f.finddim('Y')
tdim = f.finddim('T')
xnum = xdim.getLength()
ynum = ydim.getLength()
tnum = tdim.getLength()
#Add global attributes
ncfile.addgroupattr('Conventions', 'CF-1.6')
for attr in f.attributes():
ncfile.addgroupattr(attr.getName(), attr.getValues())
#Add dimension variables
dimvars = []
for dim in dims:
dname = dim.getShortName()
if dname == 'T':
var = ncfile.addvar('time', 'int', [dim])
var.addattr('units', 'hours since 1900-01-01 00:00:0.0')
var.addattr('long_name', 'Time')
var.addattr('standard_name', 'time')
var.addattr('axis', dname)
tvar = var
elif dname == 'Z':
var = ncfile.addvar('level', 'float', [dim])
var.addattr('axis', dname)
else:
var = ncfile.addvar(dim.getShortName(), 'float', [dim])
if 'Z' in dname:
var.addattr('axis', 'Z')
else:
var.addattr('axis', dname)
dimvars.append(var)
#Add variables
variables = []
for var in f.variables():
print 'Variable: ' + var.getShortName()
vdims = []
for vdim in var.getDimensions():
for dim in dims:
if vdim.getShortName() == dim.getShortName():
vdims.append(dim)
#print vdims
nvar = ncfile.addvar(var.getShortName(), var.getDataType(), vdims)
nvar.addattr('fill_value', -9999.0)
for attr in var.getAttributes():
nvar.addattr(attr.getName(), attr.getValues())
variables.append(nvar)
#Create netCDF file
ncfile.create()
#Write variable data
for dimvar, dim in zip(dimvars, f.dimensions()):
if dim.getShortName() != 'T':
ncfile.write(dimvar, array(dim.getDimValue()))
sst = datetime.datetime(1900,1,1)
for t in range(0, tnum):
st = f.gettime(t)
print st.strftime('%Y-%m-%d %H:00')
hours = (st - sst).total_seconds() // 3600
origin = [t]
ncfile.write(tvar, array([hours]), origin=origin)
for var in variables:
print 'Variable: ' + var.name
if var.ndim == 3:
data = f[str(var.name)][t,:,:]
data[data==nan] = -9999.0
origin = [t, 0, 0]
shape = [1, ynum, xnum]
data = data.reshape(shape)
ncfile.write(var, data, origin=origin)
else:
znum = var.dims[1].getLength()
for z in range(0, znum):
data = f[str(var.name)][t,z,:,:]
data[data==nan] = -9999.0
origin = [t, z, 0, 0]
shape = [1, 1, ynum, xnum]
data = data.reshape(shape)
ncfile.write(var, data, origin=origin)
#Close netCDF file
ncfile.close()
print 'Finished!'

#--------------------------------------------------------         
# Author: Yaqiang Wang                                           
# Date: 2016-4-12                                                
# Purpose: Convert GrADS data to netCDF data   
# Note: Sample                                                    
#----------------------------------------------------------- 
 
infn = 'D:/Temp/grads/model.ctl'    #Input GrADS file 
outfn = 'D:/Temp/grads/model.nc'    #Output netCDF file 
 
#Open GrADS file 
f = addfile(infn) 
 
#New netCDF file 
ncfile = addfile(outfn, 'c') 
 
#Add dimensions 
dims = [] 
for dim in f.dimensions(): 
    dims.append(ncfile.adddim(dim.getShortName(), dim.getLength())) 
xdim = f.finddim('X') 
ydim = f.finddim('Y') 
tdim = f.finddim('T') 
xnum = xdim.getLength() 
ynum = ydim.getLength() 
tnum = tdim.getLength() 
 
#Add global attributes 
ncfile.addgroupattr('Conventions', 'CF-1.6') 
for attr in f.attributes(): 
    ncfile.addgroupattr(attr.getName(), attr.getValues()) 
 
#Add dimension variables 
dimvars = [] 
for dim in dims: 
    dname = dim.getShortName() 
    if dname == 'T': 
        var = ncfile.addvar('time', 'int', [dim]) 
        var.addattr('units', 'hours since 1900-01-01 00:00:0.0') 
        var.addattr('long_name', 'Time') 
        var.addattr('standard_name', 'time') 
        var.addattr('axis', dname) 
        tvar = var 
    elif dname == 'Z': 
        var = ncfile.addvar('level', 'float', [dim]) 
        var.addattr('axis', dname) 
    else: 
        var = ncfile.addvar(dim.getShortName(), 'float', [dim]) 
        if 'Z' in dname: 
            var.addattr('axis', 'Z') 
        else: 
            var.addattr('axis', dname) 
    dimvars.append(var) 
 
#Add variables 
variables = [] 
for var in f.variables():    
    print 'Variable: ' + var.getShortName() 
    vdims = [] 
    for vdim in var.getDimensions(): 
        for dim in dims: 
            if vdim.getShortName() == dim.getShortName(): 
                vdims.append(dim) 
    #print vdims 
    nvar = ncfile.addvar(var.getShortName(), var.getDataType(), vdims) 
    nvar.addattr('fill_value', -9999.0) 
    for attr in var.getAttributes(): 
        nvar.addattr(attr.getName(), attr.getValues()) 
    variables.append(nvar) 
 
#Create netCDF file 
ncfile.create() 
 
#Write variable data 
for dimvar, dim in zip(dimvars, f.dimensions()): 
    if dim.getShortName() != 'T': 
        ncfile.write(dimvar, array(dim.getDimValue())) 
 
sst = datetime.datetime(1900,1,1) 
for t in range(0, tnum): 
    st = f.gettime(t) 
    print st.strftime('%Y-%m-%d %H:00') 
    hours = (st - sst).total_seconds() // 3600 
    origin = [t] 
    ncfile.write(tvar, array([hours]), origin=origin) 
    for var in variables: 
        print 'Variable: ' + var.name 
        if var.ndim == 3: 
            data = f[str(var.name)][t,:,:]    
            data[data==nan] = -9999.0         
            origin = [t, 0, 0] 
            shape = [1, ynum, xnum] 
            data = data.reshape(shape) 
            ncfile.write(var, data, origin=origin) 
        else: 
            znum = var.dims[1].getLength() 
            for z in range(0, znum): 
                data = f[str(var.name)][t,z,:,:] 
                data[data==nan] = -9999.0 
                origin = [t, z, 0, 0] 
                shape = [1, 1, ynum, xnum] 
                data = data.reshape(shape) 
                ncfile.write(var, data, origin=origin) 
 
#Close netCDF file 
ncfile.close() 
 
print 'Finished!'

兰溪之水 · 发表于 2016-4-15 16:47:48

这里的GrADS数据应该是一般的二进制文件吧？用ctl描述的grib应该不包括在内？

MeteoInfo · 发表于 2016-4-15 19:22:41

兰溪之水发表于 2016-4-15 16:47
这里的GrADS数据应该是一般的二进制文件吧？用ctl描述的grib应该不包括在内？

GRIB数据转换用这个：MeteoInfoLab脚本示例：GRIB转netCDF
http://bbs.06climate.com/forum.p ... 055&fromuid=106
(出处: 气象家园)

my251394667 · 发表于 2016-5-27 19:06:32

王老师，
假设如下脚本
fn=W_NAFP_C_ECMF_20160520174829_P_C1D05201200052012001.grib2
f = addfile(fn)
接下来怎么获取这个grib2文件中时间的个数？

MeteoInfo · 发表于 2016-5-28 00:02:03

my251394667 发表于 2016-5-27 19:06
王老师，
假设如下脚本
fn=W_NAFP_C_ECMF_20160520174829_P_C1D05201200052012001.grib2

tn = f.timenum()

qxjy009 · 发表于 2020-11-23 17:26:17

老师，里面不是显示可以打开grads格式资料吗，为什么要转呢，我刚试着直接打开grads格式文件，好像出不来，是要转了才可以打开吗

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