Python 'rawpy._rawpy.RawPy' object has no attribute 'imread' after second pass

I try to process a series of DNG raw picture files and it all works well for the first pass (first fils). When I try to read the second DNG file during the second pass through the for-next loop, I receive the error message 'rawpy._rawpy.RawPy' object has no attribute 'imread' when executing the line "with raw.imread(file) as raw:".

import numpy as np
import rawpy as raw
import pyexiv2

from scipy import stats
for file in list:
    metadata = pyexiv2.ImageMetadata(file)
    metadata.read()
    with raw.imread(file) as raw:
       rgb16 = raw.postprocess(gamma=(1,1), no_auto_bright=True, output_bps=16)
       avgR=stats.describe(np.ravel(rgb16[:,:,0]))[2]
       avgG=stats.describe(np.ravel(rgb16[:,:,1]))[2]
       avgB=stats.describe(np.ravel(rgb16[:,:,2]))[2]
   print i,file,'T=', metadata['Exif.PentaxDng.Temperature'].raw_value,'C',avgR,avgG,avgB
   i+=1

I tried already to close the raw object but from googling I understand that is not necessary when a context manager is used. Help or suggestions are very welcome. Thanks in advance.

You're overwriting your alias of the rawpy module (raw) with the image you're reading. That means you'll get an error on the second pass through the loop.

import rawpy as raw      # here's the first thing named "raw"
#...

for file in list:
    #...

    with raw.imread(file) as raw:    # here's the second
        #...

Pick a different name for one of the variables and your code should work.