title: QGIS python - get units of the raster
body: <p>In QGIS with pyQgis I would like to determine if input raster has units in degrees or metres. 
  <a href="https://www.gislite.com/tutorial/k8022" rel="nofollow noreferrer">Here</a> I learned I can get projection from raster using GDAL:</p>
  
  <pre><code>inRaster = gdal.Open(rasterInPath,GA_ReadOnly)
  projRef = inRaster.GetProjection()
  print(projRef)
  </code></pre>
  
  <p>what's gives me string for raster with EPSG 4326:</p>
  
  <pre><code>GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433],AUTHORITY["EPSG","4326"]]
  </code></pre>
  
  <p>and for raster with EPSG 3857:</p>
  
  <pre><code>PROJCS["WGS 84 / Pseudo-Mercator",GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4326"]],PROJECTION["Mercator_1SP"],PARAMETER["central_meridian",0],PARAMETER["scale_factor",1],PARAMETER["false_easting",0],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["X",EAST],AXIS["Y",NORTH],EXTENSION["PROJ4","+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs"],AUTHORITY["EPSG","3857"]]
  </code></pre>
  
  <p>I guess I can do:</p>
  
  <pre><code>isInMetres = "PROJCS" in projRef
  </code></pre>
  
  <p>But is there any other solution? I don't consider this very readable and not sure if I can cover all corner cases this way (e.g. missing projRef). Dont need to be necessary with GDAL.</p>