python - 如何将日期读入 netcdf4 变量？

Question

我正在尝试使用 Python 将日期放入 netcdf4 变量中。我制作了一个数组 mom，其中包含 30 次日期，格式为 YYYY/MM/DD;hh:mm:ss。必须是这个格式。该脚本有效并且没有给出任何错误，但是当我查看 netcdf 文件中的数据时，part_starttime =“222222222222222222222222222222”; (所以 30 乘以 2)才是变量中真正的内容。我如何将我的日期而不是两个日期放在那里？

import netCDF4 as nc4
import numpy as np

lon= np.loadtxt('Longitude_Sea_30.txt')#latitude
lat = np.loadtxt('Latitude_Sea_30.txt')#longitude
z = np.tile(1,30)#depth
tijd=np.tile(1,30)#time

Part = np.tile(3,30)

llon=len(lon)
llat=len(lat)
lz=len(z)
ltijd=len(tijd)
lPart=len(Part)

ntime=1
nparticles=30
mom=np.tile("2013/04/22;00:00:00",30)

#create netcdf4 file
f = nc4.Dataset('Stack2.nc','w', format='NETCDF4')

#create group 
Jellygrp = f.createGroup('Jelly')

#Define dimensions

Jellygrp.createDimension('time',None)#
Jellygrp.createDimension('tlendim', 23)  #time
Jellygrp.createDimension('Y009', lPart)
Jellygrp.createDimension('X006', llon) #lon
Jellygrp.createDimension('X007', llat) #lat
Jellygrp.createDimension('X008', lz) #depth

#define arrays

part_xpos= np.zeros((ntime,nparticles))
part_ypos= np.zeros((ntime,nparticles))
part_zpos= np.zeros((ntime,nparticles))
part_starttime= np.zeros((ntime,nparticles))

#create variables

time = Jellygrp.createVariable('time', 'S1', ('time','tlendim'))

part_xpos=Jellygrp.createVariable('part_xpos', 'd', ('time','X006'))
part_ypos=Jellygrp.createVariable('part_ypos','d',('time','X007'))
part_zpos=Jellygrp.createVariable('part_zpos','d',('time','X008'))
part_starttime=Jellygrp.createVariable('part_starttime','S1',
('time','Y009'))

#Passing data into variables

part_xpos[0,:] =lon[:] 
part_ypos[0,:] =lat[:]
part_zpos[0,:] = z[:]
part_starttime[0,:] = mom[:]
print(f.groups['Jelly'])

f.close()

Answer 1

这是由变量和初始化的格式引起的。您的变量是一个字符数组。您的字符数组仅保存每个字符串的第一个值，这就是您得到三十个 2 的原因。下面的代码使用空字符值初始化空数组。每个数组都是一个字符数组，其元素创建日期时间戳。下面是更新后的代码，以使用字符数组来存储所需的字符串数据:

>>> import netCDF4 as nc4
>>> import numpy as np
>>> 
>>> lon= np.loadtxt('Longitude_Sea_30.txt')#latitude
>>> lat = np.loadtxt('Latitude_Sea_30.txt')#longitude
>>> z = np.tile(1,30)#depth
>>> tijd=np.tile(1,30)#time

# I changed the name to part because Part looked like it was a keyword in 
# your example.  I also changed it to fill with an empty character because I 
# am using it to initialize a character array.
>>> part = np.tile('', 30)
>>> part
array(['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
   '', '', '', '', '', '', '', '', '', '', '', '', ''],
  dtype='<U1')
>>> llon=len(lon)
>>> llat=len(lat)
>>> lz=len(z)
>>> ltijd=len(tijd)
# creating length part with part
>>> lPart=len(part)
>>> ntime=1
>>> nparticles=30
>>> 
# This is the datetime string given in your example.  I just set it as a variable.
>>> datetime_string = '2013/04/22;00:00:00'
# I am using full so I can set the empty characters to '' explicitly.
>>> mom = np.full((30, len(datetime_string)), fill_value='')
>>> mom
array([['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', ''],
   ['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
    '', '']],
  dtype='<U1')
# Now I am filling in values for mom.  You must break the string into its
# character parts to take advantage of the np.array functionality.
>>> for i in range(0,30):
...     mom[i] = list(datetime_string)
... 
>>> mom
array([['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0'],
   ['2', '0', '1', '3', '/', '0', '4', '/', '2', '2', ';', '0', '0',
    ':', '0', '0', ':', '0', '0']],
  dtype='<U1')

# open your dataset for writing
>>> f = nc4.Dataset('Stack2.nc','w', format='NETCDF4')
>>> Jellygrp = f.createGroup('Jelly')
>>> Jellygrp.createDimension('time',None)
<class 'netCDF4._netCDF4.Dimension'> (unlimited): name = 'time', size = 0

# Create the tlendim with the length of your datetime_string
>>> Jellygrp.createDimension('tlendim', len(datetime_string))
<class 'netCDF4._netCDF4.Dimension'>: name = 'tlendim', size = 19

>>> Jellygrp.createDimension('Y009', lPart)
<class 'netCDF4._netCDF4.Dimension'>: name = 'Y009', size = 30

>>> Jellygrp.createDimension('X006', llon) #lon
<class 'netCDF4._netCDF4.Dimension'>: name = 'X006', size = 30

>>> Jellygrp.createDimension('X007', llat) #lat
<class 'netCDF4._netCDF4.Dimension'>: name = 'X007', size = 30

>>> Jellygrp.createDimension('X008', lz)
<class 'netCDF4._netCDF4.Dimension'>: name = 'X008', size = 30

>>> part_xpos= np.zeros((ntime,nparticles))
>>> part_ypos= np.zeros((ntime,nparticles))
>>> part_zpos= np.zeros((ntime,nparticles))

# Initialize your array to include the length of your desired datetime_string, making it 3 dimensional
>>> part_starttime_array= np.full((ntime,nparticles,len(datetime_string)), fill_value='')

# create your variables
>>> time = Jellygrp.createVariable('time', 'S1', ('time','tlendim'))
>>> part_xpos=Jellygrp.createVariable('part_xpos', 'd', ('time','X006'))
>>> part_ypos=Jellygrp.createVariable('part_ypos','d',('time','X007'))
>>> part_zpos=Jellygrp.createVariable('part_zpos','d',('time','X008'))

# you need to add the length of the datetime_string as a dimension
>>> part_starttime=Jellygrp.createVariable('part_starttime','S1', ('time', 'Y009', 'tlendim'))

# assign to your netCDF variables.
>>> part_xpos[0,:] =lon[:] 
>>> part_ypos[0,:] =lat[:]
>>> part_zpos[0,:] = z[:]
>>> part_starttime[0,:] = mom[:]
>>> f.close()

现在您可以使用ncdump来查看part_starttime变量。

$ ncdump -v part_starttime Stack2.nc 
netcdf Stack2 {

// global attributes:
        :_NCProperties = 
"version=1|netcdflibversion=4.4.1.1|hdf5libversion=1.8.18" ;

group: Jelly {
  dimensions:
    time = UNLIMITED ; // (1 currently)
    tlendim = 19 ;
    Y009 = 30 ;
    X006 = 30 ;
    X007 = 30 ;
    X008 = 30 ;
  variables:
    char time(time, tlendim) ;
    double part_xpos(time, X006) ;
    double part_ypos(time, X007) ;
    double part_zpos(time, X008) ;
    char part_starttime(time, Y009, tlendim) ;
  data:

   part_starttime =
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00",
  "2013/04/22;00:00:00" ;
  } // group Jelly
}