I am trying to convert a .csv file to a netCDF4 via Python but I am having trouble figuring out how I can store information from a .csv table format into a netCDF. My main concern is how do we declare the variables from the columns into a workable netCDF4 format? Everything I have found is normally extracting information from a netCDF4 to a .csv or ASCII. I have provided the sample data, sample code, and my errors for declaring the appropriate arrays. Any help would be much appreciated.
The sample table is below:
Station Name Country Code Lat Lon mn.yr temp1 temp2 temp3 hpa Somewhere US 12340 35.52 23.358 1.19 -8.3 -13.1 -5 69.5 Somewhere US 12340 2.1971 -10.7 -13.9 -7.9 27.9 Somewhere US 12340 3.1971 -8.4 -13 -4.3 90.8 My sample code is:
#!/usr/bin/env python
import scipy import numpy import netCDF4 import csv from numpy import arange, dtype #Declare empty arrays
v1 = [] v2 = [] v3 = [] v4 = [] # Open csv file and declare variable for arrays for each heading
f = open('station_data.csv', 'r').readlines() for line in f[1:]: fields = line.split(',') v1.append(fields[0]) #station v2.append(fields[1])#country v3.append(int(fields[2]))#code v4.append(float(fields[3]))#lat v5.append(float(fields[3]))#lon #more variables included but this is just an abridged list print v1 print v2 print v3 print v4 #convert to netcdf4 framework that works as a netcdf
ncout = netCDF4.Dataset('station_data.nc','w') # latitudes and longitudes. Include NaN for missing numbers
lats_out = -25.0 + 5.0*arange(v4,dtype='float32') lons_out = -125.0 + 5.0*arange(v5,dtype='float32') # output data.
press_out = 900. + arange(v4*v5,dtype='float32') # 1d array press_out.shape = (v4,v5) # reshape to 2d array temp_out = 9. + 0.25*arange(v4*v5,dtype='float32') # 1d array temp_out.shape = (v4,v5) # reshape to 2d array # create the lat and lon dimensions.
ncout.createDimension('latitude',v4) ncout.createDimension('longitude',v5) # Define the coordinate variables. They will hold the coordinate information
lats = ncout.createVariable('latitude',dtype('float32').char,('latitude',)) lons = ncout.createVariable('longitude',dtype('float32').char,('longitude',)) # Assign units attributes to coordinate var data. This attaches a text attribute to each of the coordinate variables, containing the units.
lats.units = 'degrees_north' lons.units = 'degrees_east' # write data to coordinate vars.
lats[:] = lats_out lons[:] = lons_out # create the pressure and temperature variables
press = ncout.createVariable('pressure',dtype('float32').char,('latitude','longitude')) temp = ncout.createVariable('temperature',dtype('float32').char,'latitude','longitude')) # set the units attribute.
press.units = 'hPa' temp.units = 'celsius' # write data to variables.
press[:] = press_out temp[:] = temp_out ncout.close() f.close() error:
Traceback (most recent call last): File "station_data.py", line 33, in <module> v4.append(float(fields[3]))#lat ValueError: could not convert string to float: