netCDF4 处理nc文件总结
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netCDF4 处理nc文件总结
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創建nc文件
# 數據類型包括:f4(32位浮點數),f8(64位浮點數),i1(8位符號整型),i2(16位符號整型),i4(32位符號整型),i8(64位符號整型),
# u1(8位無符號整型),u2(16位無符號整型),u4(32位無符號整型),u8(64位無符號整型),S1(單字符字符串)
with nc.Dataset(nc_name, 'w', format='NETCDF4') as fnc:
fnc.createDimension('lat', 3541) # 確定維度大小
fnc.createDimension('lon', 6165)
# 變量名 數據類型 維度大小
lat = fnc.createVariable('lat', 'f4', ('lat',)) # 創建變量
lat.long_name = "latitude" # 該變量的名稱
lat.units = "degrees_north" # 該變量的單位
lon = fnc.createVariable('lon', 'f4', ('lon',))
lon.long_name = "longitude"
lon.units = "degrees_east"
# 是否壓縮數據 壓縮級別(1-9級) 默認初始填充值
alt = fnc.createVariable('alt', 'f4', ('lat', 'lon'), zlib=True, complevel=9, fill_value=-9999)
alt.long_name = 'height above sea level'
alt.coordinates = 'lat lon alt'
alt.units = 'meters'
alt.positive = 'up' # 高度的方向 up為向上
PRS = fnc.createVariable('PRS', 'short', ('lat', 'lon'), zlib=True, complevel=9, fill_value=-9999) # 氣壓
PRS.long_name = 'station pressure'
PRS.units = 'hPa'
PRS.missing_value = -9999 # 默認缺測填充
PRS.coordinates = 'lat lon alt'
PRS.add_offset = np.float32(0.0) # 增加偏移
PRS.scale_factor = np.float32(0.1) # 比例偏移 實際值存入自動擴大10倍(除以0.1),取出自動縮小10倍(乘以0.1)
PRS.valid_min = 5200 # 限制存入最小值 小于最小為缺測
PRS.valid_max = 10850 # 限制存入最大值 大于最大為缺測
# 給變量賦值 賦值的數據維度--必須和創建變量時指定的維度大小一致
fnc.variables['lat'][:] = np.arange(53.56, 18.16, -0.01)
fnc.variables['lon'][:] = np.arange(73.44, 135.09, 0.01)
fnc.variables['alt'][:] = np.array(data['alt'], dtype='float').reshape(3541, 6165)
fnc.variables['PRS'][:] = np.array(data['PRS'], dtype='float').reshape(3541, 6165)
fnc.author = 'ecoweather' # 創建文件作者
fnc.createdate = '%s' % datetime.datetime.now().strftime('%Y-%m-%d %H:%M') # 創建文件時間
創建有時間變量的nc文件
with nc.Dataset(nc_name, 'w', format='NETCDF4') as fnc:
fnc.createDimension('time', 24) # 確定維度大小
fnc.createDimension('size', 10447)
tt = fnc.createVariable('time', 'i4', 'time')
tt.long_name = 'time'
# 起始小時時間 它會自動根據你賦值的數據,從起始小時累加
tt.units = 'hours since %s' % datetime.datetime.strptime(start_time, '%Y%m%d%H%M%S').strftime('%Y-%m-%d %H:%M:%S')
# 日歷(公歷)
tt.calendar = "gregorian"
sta = fnc.createVariable('sta', 'i4', ('size',)) # 創建變量
sta.coordinates = 'lat lon alt'
sta.long_name = 'station number' # 站號
lat = fnc.createVariable('lat', 'f4', ('size',))
lat.long_name = "latitude"
lat.units = "degrees_north"
lon = fnc.createVariable('lon', 'f4', ('size',))
lon.long_name = "longitude"
lon.units = "degrees_east"
PRE_1m = fnc.createVariable('PRE_1m', 'f4', ('time', 'size'), zlib=True, complevel=9, fill_value=-9999) # 一分鐘降水
PRE_1m.long_name = 'precipitation of 1 min'
PRE_1m.units = 'mm'
PRE_1m.missing_value = -9999
PRE_1m._CoordinateAxes = 'lat lon'
fnc.variables['time'][:] = np.array([i for i in range(1, 25)])
fnc.variables['sta'][:] = np.array(dictknn.index.tolist())
fnc.variables['lat'][:] = np.array(dictknn['lat'].tolist())
fnc.variables['lon'][:] = np.array(dictknn['lon'].tolist())
fnc.variables['PRE_1m'][:] = np.array(data)
讀取nc文件
def read_nc(ncpath: str):
print('讀取 nc 文件 %s' % ncpath)
f = nc.Dataset(ncpath, 'r')
# 獲取nc文件中的變量名
var_key = list(f.variables.keys())
var_len = f.variables['lat'][:].shape
# print(var_key, var_len)
# 創建DataFrame存放數據,一列一類數據
nc_data = pd.DataFrame(index=range(var_len[0]), columns=var_key[1:], dtype='short')
for e in var_key:
# 獲取變量數據
vardata = f.variables[e][:]
size = vardata.shape
# print('{}-{}'.format(e, size)) # (3541, 6165) 3541行,每行6165個
if len(size) == 1:
if e == 'sta':
# nc_data[e] = vardata
nc_data.index = vardata
else:
nc_data[e] = list(map(lambda s: float('%s' % s), vardata))
else:
nc_data[e] = list(vardata)
# print(f.variables)
f.close()
print(nc_data)
return nc_data
創建群組
with nc.Dataset(nc_name, 'w', format='NETCDF4') as fnc:
# 創建一個群組
group1 = fnc.createGroup('LatLon_1441X2880')
group1.createDimension('lat', 1441) # 確定維度大小
group1.createDimension('lon', 2880) # 確定維度大小
lat1 = group1.createVariable('lat', 'f4', ('lat',), zlib=True, complevel=9, fill_value=-9999)
lat1.units = "degrees_north"
lon1 = group1.createVariable('lon', 'f4', ('lon',), zlib=True, complevel=9, fill_value=-9999)
lon1.units = "degrees_east"
group1.variables['lat'][:] = data[1441]['lat']
group1.variables['lon'][:] = data[1441]['lon']
for elem in data[1441]['value']:
d = group1.createVariable(elem['name'], 'short', ('lat', 'lon'), zlib=True, complevel=9, fill_value=-9999)
d.units = elem['units']
d.missing_value = -9999
d.add_offset = np.float32(0.0)
d.scale_factor = np.float32(0.1)
group1.variables[elem['name']][:] = elem['value']
group1.close # 關閉群組, 注意,這里沒有括號
# 創建一個群組
group2 = fnc.createGroup('LatLon_281X361')
group2.createDimension('lat1', 281) # 確定維度大小
group2.createDimension('lon1', 361) # 確定維度大小
lat2 = group2.createVariable('lat', 'f4', ('lat1',), zlib=True, complevel=9, fill_value=-9999)
lat2.units = "degrees_north"
lon2 = group2.createVariable('lon', 'f4', ('lon1',), zlib=True, complevel=9, fill_value=-9999)
lon2.units = "degrees_east"
group2.variables['lat'][:] = data[281]['lat']
group2.variables['lon'][:] = data[281]['lon']
for elem in data[281]['value']:
d = group2.createVariable(elem['name'], 'short', ('lat1', 'lon1'), zlib=True, complevel=9, fill_value=-9999)
d.units = elem['units']
d.missing_value = -9999
d.add_offset = np.float32(0.0)
d.scale_factor = np.float32(0.1)
group2.variables[elem['name']][:] = elem['value']
group2.close
fnc.author = 'ecoweather'
fnc.createdate = '%s' % datetime.datetime.now().strftime('%Y-%m-%d %H:%M')
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