#!/usr/bin/env python
# coding: utf-8

# # Check the start/stop time of a netcdf/OPeNDAP dataset

# In[1]:


import netCDF4
import numpy as np


# In[2]:


def start_stop(url,tvar):
    nc = netCDF4.Dataset(url)
    ncv = nc.variables
    time_var = ncv[tvar]
    first = netCDF4.num2date(time_var[0],time_var.units)
    last = netCDF4.num2date(time_var[-1],time_var.units)

    print(first.strftime('%Y-%b-%d %H:%M'))
    print(last.strftime('%Y-%b-%d %H:%M'))


# In[3]:


url='http://hfrnet.ucsd.edu/thredds/dodsC/HFR/USWC/6km/hourly/RTV/HFRADAR,_US_West_Coast,_6km_Resolution,_Hourly_RTV_best.ncd'
tvar='time'
start_stop(url,tvar)


# In[4]:


nc = netCDF4.Dataset(url)
ncv = nc.variables
t = ncv[tvar][:]
print(ncv[tvar].units)


# Calculate the average time step

# In[5]:


print np.mean(np.diff(t))


# So we have time steps of about 1 hour

# Now calculate the unique time steps

# In[6]:


print(np.unique(np.diff(t)).data)


# So there are gaps of 2, 3, 6, 9, 10, 14 and 19 hours in the otherwise hourly data