title: Extract area from high resolution netcdf file python
body: <p>I am trying to extract an area from a netcdf file by longitude and latitude.
  However the resolution is much higher than 1x1 degree.
  How would you extract an area then, e.g. lon: 30-80 and lat: 30-40.
  The file can be found here: <a href="https://drive.google.com/open?id=1zX-qYBdXT_GuktC81NoQz9xSxSzM-CTJ" rel="nofollow noreferrer">https://drive.google.com/open?id=1zX-qYBdXT_GuktC81NoQz9xSxSzM-CTJ</a></p>
  
  <p>Keys and shapes are as follows:</p>
  
  <pre><code>odict_keys(['crs', 'lat', 'lon', 'Band1'])
  crs ()
  lat (25827,)
  lon (35178,)
  Band1 (25827, 35178)
  </code></pre>
  
  <p>I have tried this, but with the high resolution, it doesn't refer to the actual longitude/langitude.</p>
  
  <pre><code>from netCDF4 import Dataset
  import numpy as np
  import matplotlib.pyplot as plt
  
  file = path + '20180801-ESACCI-L3S_FIRE-BA-MODIS-AREA_3-fv5.1-JD.nc'
  fh = Dataset(file)
  longitude = fh.variables['lon'][:]
  latitude = fh.variables['lat'][:]
  band1 = fh.variables['Band1'][:30:80,30:40]
  </code></pre>