CODEWITHSUNDEEP
pythoncsvnetcdfnetcdf4
rnvs1116
rnvs1116

Reputation: 39

Convert netCDF file to csv using Python

I am trying to convert netCDF files to csv. Files are stored in thredds server.I have written below code which reads files from Thredds server and select six variables from the list of variables present in netCDF files and stored them locally in csv format.

from datetime import datetime
from netCDF4 import Dataset
import netCDF4
import pandas as pd
import csv
def get_thredds_url(datetime_group, forecast_hour):
    base_url="path"
    thredds_url="path"
    cycle_hour = "%02d" % datetime_group.hour
    file_str=datetime_group.strftime("%Y%m%d%H")+"/gfs.t%sz.pgrb2.0p25.f%03d" % \
        (cycle_hour, forecast_hour)
    url = base_url + thredds_url + file_str
    return (url)

Below code shows the required variables.

def main():

    datetime_group = datetime(2017, 9, 26, 0)
    forecast_hour = 240

    url = get_thredds_url(datetime_group, forecast_hour)
    print (url)

    nc_handle=Dataset(url)
    #print (nc_handle.variables.keys())
    lat=nc_handle.variables['lat'][:]
    lon=nc_handle.variables['lon'][:]
    issue_time=nc_handle.variables['time'][:]
    valid_time=nc_handle.variables['time1'][:]
    temp=nc_handle.variables['Temperature_height_above_ground'][:]
    dewpoint_temp=lat=nc_handle.variables['Dewpoint_temperature_height_above_ground'][:]
    dtime = netCDF4.num2date(issue_time[:],units=units)


 tmp = pd.Series(temp, index=dtime) 

    tmp.to_csv('temp.csv',index=True, header=True)
    csvwriter = csv.writer(tmp,  delimiter=',')
    print (csvwriter)





if __name__ == "__main__":
    main()

Problem: I am not able to write file into csvnformat which contains all the variables such as lat,lon,time,time1,Temperature_height_above_ground. Desired output is given below:

tmp.csv

 lat lon time time1 Temperature_height_above_ground
1 ... .. ...  ....  ......
2 ... .. ...  ....  ......
3 ... .. ...  ....  ......

Can anyone help me out me with this?

Thanks in advance!

Upvotes: -1

Views: 2281

Answers (2)

AYESHA JAVED
AYESHA JAVED

Reputation: 89

You can Convert the NETCDF into CSV using this simple code in Python step wise. We need 2 main libraries

a-NetCDF-4 :-
(Network Common Data Form, version 4) description. NetCDF is a set of software libraries and self-describing, machine-independent data formats for array-oriented scientific data*

b-xarray: xarray (formerly xray) is an open source project and Python package that makes working with labelled multi-dimensional arrays simple, efficient, and fun!

Import libraries:

   import netCDF4 as nc
   import xarray as xr

   data = nc.Dataset(r'C:\\Users\\Admin\\Desktop\\LDN DATA NC FORMAT\\20210312_0257.nc', 'r')
   dataset = xr.open_dataset(xr.backends.NetCDF4DataStore(data))
   df = dataset.to_dataframe()
   csv_data=df.to_csv('C:\\Users\\Admin\\Desktop\\LDN DATA NC FORMAT\\20210312_0257.nc.csv')
   print('\nCSV String:\n', csv_data)

Screenshot #1:

enter image description here

Screenshot #2:

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After finish the execution csv file save in the same folder which is provided

Upvotes: 0

Burhan Khalid
Burhan Khalid

Reputation: 174708

I think what you are looking for is this:

with open('temp.csv', 'w') as f:
  writer = csv.writer(f, delimiter=',')
  # write the header
  writer.writerow(['lat',
                   'lon',
                   'time',
                   'time1',
                   'temp_height_above_ground',
                   'dewpoint_temp_height_above_ground',
                   'issue_time'])

  # collect the columns as rows
  rows = zip(lat,lon,issue_time,valid_time,temp,dewpoint_temp,dtime)

  for row in rows:
    writer.writerow(row)

Upvotes: 0

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