Python: Getting data from a function

Question

I'm trying to get data from this function:

def read_images(path, sz=None):
"""Reads the images in a given folder, resizes images on the fly if size is given.
Args:
 path: Path to a folder with subfolders representing the subjects (persons).
 sz: A tuple with the size Resizes
Returns:
 A list [X,y]
 X: The images, which is a Python list of numpy arrays.
 y: The corresponding labels (the unique number of the subject, person) in a Python list.
"""
c = 0
X,y = [], []
for dirname, dirnames, filenames in os.walk(path):
 for subdirname in dirnames:
 subject_path = os.path.join(dirname, subdirname)
 for filename in os.listdir(subject_path):
 try:
 im = Image.open(os.path.join(subject_path, filename))
 im = im.convert("L")
 # resize to given size (if given)
 if (sz is not None):
 im = im.resize(self.sz, Image.ANTIALIAS)
 X.append(np.asarray(im, dtype=np.uint8))
 y.append(c)
 except IOError, (errno, strerror):
 print "I/O error({0}): {1}".format(errno, strerror)
 except:
 print "Unexpected error:", sys.exc_info()[0]
 raise
 c = c+1
return [X,y]

The problem is that when I call the function

[X,y] = read_images('/Trainer')

where Trainer is the folder that have the images. Now, when I call this function, the function can't reach the folder and the values of X and y are still empty. I tried to print X and print y and both values where X=[] y=[] I tried also to do it like this

TrainerPath = "C:\Users\Eng. Aladdin Hammodi\Desktop\recognizer\Trainer"
[X,y] = read_images(TrainerPath) 

but still have the same thing. What should I do?

• Adeel Ahmad: Have you tried listing your files using os.listdir('C:\Users\Eng. Aladdin Hammodi\Desktop\recognizer\Trainer')?
• aladdin hammodi: No, I haven't. What exactly I should add to the code?
• Adeel Ahmad: Exactly what I wrote above. Add it at the beginning and print the output.
• aladdin hammodi: I got this Error os.listdir('C:\Users\Eng. Aladdin Hammodi\Desktop\recognizer\Trainer') WindowsError: [Error 123] The filename, directory name, or volume label syntax is incorrect: 'C:\\Users\\Eng. Aladdin Hammodi\\Desktop\recognizer\\Trainer/*.*'

Answer 1

The \ symbol escapes characters in your string. Try using a raw string modifier, like this: TrainerPath = r"C:\Users\Eng. Aladdin Hammodi\Desktop\recognizer\Trainer"

• Alex Bausk: Have you debugged it? What does os.walk(...) return, just an empty generator or an error? at which point in the code does it break?
• aladdin hammodi: File "C:\Python27\lib\site-packages\numpy\core\shape_base.py", line 234, in vstack return _nx.concatenate([atleast_2d(_m) for _m in tup], 0) ValueError: all the input array dimensions except for the concatenation axis must match exactly >>>
• Alex Bausk: This is specific to how you concatenate numpy arrays, can't say anything without looking at the data. Perhaps try posting a separate question since this is unrelated to this one.
• aladdin hammodi: stackoverflow.com/questions/44862551/… I've posted it here

Answer 2

What happens if you escape the "\" - either by putting and r before the path ( r'C:\Users....') or like 'C:\\Users...'?