Added SpyException base class for module-specific exceptions.

Module-specific exceptions are now all derived from SpyException.

InvalidFileError is now raised instead of IOError if a file is determined
to be invalid.

New classes added:

- spectral.SpyException
- spectral.io.spyfile.InvalidFileError
- spectral.io.envi.EnviDataFileNotFoundError

Author: tboggs

spectral/__init__.py

@@ -43,6 +43,10 @@
 BIL = 1
 BIP = 2
 
+class SpyException(Exception):
+    '''Base class for spectral module-specific exceptions.'''
+    pass
+
 from .spectral import (open_image, load_training_sets, save_training_sets,
                       settings, tile_image, spy_colors, BandInfo)
 from .io import *

spectral/io/aviris.py

@@ -57,13 +57,13 @@ def open(file, band_file=None):
 
     Raises:
 
-        IOError
+        spectral.io.spyfile.InvalidFileError
     '''
     import numpy as np
     from spectral.io.bipfile import BipFile
     import os
     import glob
-    from .spyfile import find_file_path
+    from .spyfile import find_file_path, InvalidFileError
     import spectral
 
     class Params:
@@ -75,7 +75,7 @@ class Params:
     p.ncols = 614
     fileSize = os.stat(p.filename)[6]
     if fileSize % 275072 != 0:
-        raise IOError('File size not consistent with AVIRIS format.')
+        raise InvalidFileError('File size not consistent with AVIRIS format.')
     p.nrows = int(fileSize / 275072)
     p.byte_order = 1
     p.dtype = np.dtype('i2').str

spectral/io/envi.py

@@ -69,24 +69,27 @@
 envi_to_dtype = dict((k, np.dtype(v).char) for (k, v) in dtype_map)
 dtype_to_envi = dict(tuple(reversed(item)) for item in list(envi_to_dtype.items()))
 
-class EnviException(Exception):
+from spectral import SpyException
+from .spyfile import FileNotFoundError, InvalidFileError
+
+class EnviException(SpyException):
     '''Base class for ENVI file-related exceptions.'''
     pass
 
-class EnviDataTypeError(TypeError):
-    '''Exception raised when saving invalid image data type to ENVI format.
+class EnviDataTypeError(EnviException, TypeError):
+    '''Raised when saving invalid image data type to ENVI format.
     '''
     def __init__(self, dtype):
         msg = 'Image data type "{0}" can not be saved to ENVI data file. ' \
           'Call spectral.envi.get_supported_dtypes for a list of supported ' \
           'data type names.'.format(np.dtype(dtype).name)
         super(EnviDataTypeError, self).__init__(msg)
 
-class EnviFeatureNotSupported(NotImplementedError):
+class EnviFeatureNotSupported(EnviException, NotImplementedError):
     '''A specified ENVI capability is not supported by the spectral module.'''
     pass
 
-class FileNotAnEnviHeader(EnviException):
+class FileNotAnEnviHeader(EnviException, InvalidFileError):
     '''Raised when "ENVI" does not appear on the first line of the file.'''
     def __init__(self, msg):
         super(FileNotAnEnviHeader, self).__init__(msg)
@@ -97,12 +100,16 @@ def __init__(self, param):
         msg = 'Mandatory parameter "%s" missing from header file.' % param
         super(MissingEnviHeaderParameter, self).__init__(msg)
 
-class EnviHeaderParsingError(EnviException):
+class EnviHeaderParsingError(EnviException, InvalidFileError):
     '''Raised upon failure to parse parameter/value pairs from a file.'''
     def __init__(self):
         msg = 'Failed to parse ENVI header file.'
         super(EnviHeaderParsingError, self).__init__(msg)
 
+class EnviDataFileNotFoundError(EnviException, FileNotFoundError):
+    '''Raised when data file associated with a header is not found.'''
+    pass
+
 def _validate_dtype(dtype):
     '''Raises EnviDataTypeError if dtype can not be written to ENVI file.'''
     typename = np.dtype(dtype).name
@@ -273,7 +280,7 @@ def open(file, image=None):
 
     Raises:
 
-        TypeError, IOError.
+        TypeError, EnviDataFileNotFoundError
 
     If the specified file is not found in the current directory, all
     directories listed in the SPECTRAL_DATA environment variable will be
@@ -313,7 +320,10 @@ def open(file, image=None):
                     image = testname
                     break
         if not image:
-            raise IOError('Unable to determine image file name.')
+            msg = 'Unable to determine the ENVI data file name for the ' \
+              'given header file. You can specify the data file by passing ' \
+              'its name as the optional `image` argument to envi.open.'
+            raise EnviDataFileNotFoundError(msg)
     else:
         image = find_file_path(image)
 
@@ -367,15 +377,15 @@ def check_new_filename(hdr_file, img_ext, force):
     hdr_file = os.path.realpath(hdr_file)
     (base, ext) = os.path.splitext(hdr_file)
     if ext.lower() != '.hdr':
-        raise ValueError('Header file name must end in ".hdr" or ".HDR".')
+        raise EnviException('Header file name must end in ".hdr" or ".HDR".')
     image_file = base + img_ext
     if not force:
         if os.path.isfile(hdr_file):
-            raise Exception('Header file %s already exists. Use `force` '
-                            'keyword to force overwrite.' % hdr_file)
+            raise EnviException('Header file %s already exists. Use `force` '
+                                'keyword to force overwrite.' % hdr_file)
         if os.path.isfile(image_file):
-            raise Exception('Image file %s already exists. Use `force` '
-                            'keyword to force overwrite.' % image_file)
+            raise EnviException('Image file %s already exists. Use `force` '
+                                'keyword to force overwrite.' % image_file)
     return (hdr_file, image_file)
 
 
@@ -818,15 +828,15 @@ def create_image(hdr_file, metadata=None, **kwargs):
 
     # Verify minimal set of parameters have been provided
     if 'lines' not in metadata:
-        raise Exception('Number of image rows is not defined.')
+        raise EnviException('Number of image rows is not defined.')
     elif 'samples' not in metadata:
-        raise Exception('Number of image columns is not defined.')
+        raise EnviException('Number of image columns is not defined.')
     elif 'bands' not in metadata:
-        raise Exception('Number of image bands is not defined.')
+        raise EnviException('Number of image bands is not defined.')
     elif 'samples' not in metadata:
-        raise Exception('Number of image columns is not defined.')
+        raise EnviException('Number of image columns is not defined.')
     elif 'data type' not in metadata:
-        raise Exception('Image data type is not defined.')
+        raise EnviException('Image data type is not defined.')
 
     params = gen_params(metadata)
     dt = np.dtype(params.dtype).char

spectral/io/erdas.py

@@ -105,13 +105,13 @@ def open(file):
 
     Raises:
 
-        IOError
+        spectral.io.spyfile.InvalidFileError
     '''
 
     import numpy as np
     import spectral
     from .bilfile import BilFile
-    from .spyfile import find_file_path
+    from .spyfile import find_file_path, InvalidFileError
 
 
     # ERDAS 7.5 headers do not specify byte order so we'll guess little endian.
@@ -141,10 +141,11 @@ class Params:
     elif lh["packing"] == 0:
         p.dtype = np.dtype('i1').str
     elif lh["packing"] == 1:
-        raise Exception(
-            '4-bit data type not supported in SPy ERDAS/Lan format handler.')
+        msg = '4-bit data type not supported in SPy ERDAS/Lan format handler.'
+        raise InvalidFileError(msg)
     else:
-        raise Exception('Unexpected data type specified in ERDAS/Lan header.')
+        msg = 'Unexpected data type specified in ERDAS/Lan header.'
+        raise InvalidFileError(msg)
     if spectral.byte_order != 0:
         p.dtype = np.dtype(p.dtype).newbyteorder().str
 
@@ -168,6 +169,7 @@ def read_erdas_lan_header(fileName, byte_order=0):
     import sys
     import spectral
     from spectral.utilities.python23 import IS_PYTHON3, typecode
+    from .spyfile import InvalidFileError
 
     if IS_PYTHON3:
         import builtins
@@ -183,7 +185,7 @@ def read_erdas_lan_header(fileName, byte_order=0):
 
     h["type"] = f.read(6)
     if h["type"] not in (b'HEAD74', b'HEADER'):
-        raise IOError('Does not look like an ERDAS Lan header.')
+        raise InvalidFileError('Does not look like an ERDAS Lan header.')
 
     # Read all header data into arrays
     word = array(typecode('h'))

spectral/io/spyfile.py

@@ -112,9 +112,14 @@
 
 import numpy
 import numpy as np
+from spectral import SpyException
 from spectral.spectral import Image
 
-class FileNotFoundError(Exception):
+class FileNotFoundError(SpyException):
+    pass
+
+class InvalidFileError(SpyException):
+    '''Raised when file contents are invalid for the exepected file type.'''
     pass
 
 def find_file_path(filename):

spectral/tests/envi.py

@@ -284,6 +284,21 @@ def test_missing_ENVI_in_header_fails(self):
         else:
             raise Exception('Failed to raise EnviMissingHeaderParameter')
 
+    def test_open_missing_data_raises_envidatafilenotfounderror(self):
+        '''EnviDataFileNotFound should be raise if data file is not found.'''
+        import os
+        import spectral as spy
+        img = spy.open_image('92AV3C.lan')
+        fname = os.path.join(testdir, 'header_without_data.hdr')
+        spy.envi.save_image(fname, img, ext='.img')
+        os.unlink(os.path.splitext(fname)[0] + '.img')
+        try:
+            img2 = spy.envi.open(fname)
+        except spy.envi.EnviDataFileNotFoundError:
+            pass
+        else:
+            raise Exception('Expected EnviDataFileNotFoundError')
+
 def run():
     print('\n' + '-' * 72)
     print('Running ENVI tests.')