Fix and simplify SEMEION dataset (#332)

Author: fmassa

torchvision/datasets/semeion.py

@@ -46,39 +46,12 @@ def __init__(self, root, transform=None, target_transform=None, download=True):
         self.data = []
         self.labels = []
         fp = os.path.join(root, self.filename)
-        file = open(fp, 'r')
-        data = file.read()
-        file.close()
-        dataSplitted = data.split("\n")[:-1]
-        datasetLength = len(dataSplitted)
-        i = 0
-        while i < datasetLength:
-            # Get the 'i-th' row
-            strings = dataSplitted[i]
-
-            # Split row into numbers(string), and avoid blank at the end
-            stringsSplitted = (strings[:-1]).split(" ")
-
-            # Get data (which ends at column 256th), then in a numpy array.
-            rawData = stringsSplitted[:256]
-            dataFloat = [float(j) for j in rawData]
-            img = np.array(dataFloat[:16])
-            j = 16
-            k = 0
-            while j < len(dataFloat):
-                temp = np.array(dataFloat[k:j])
-                img = np.vstack((img, temp))
-
-                k = j
-                j += 16
-
-            self.data.append(img)
-
-            # Get label and convert it into numbers, then in a numpy array.
-            labelString = stringsSplitted[256:]
-            labelInt = [int(index) for index in labelString]
-            self.labels.append(np.array(labelInt))
-            i += 1
+        data = np.loadtxt(fp)
+        # convert value to 8 bit unsigned integer
+        # color (white #255) the pixels
+        self.data = (data[:, :256] * 255).astype('uint8')
+        self.data = np.reshape(self.data, (-1, 16, 16))
+        self.labels = np.nonzero(data[:, 256:])[1]
 
     def __getitem__(self, index):
         """
@@ -91,9 +64,6 @@ def __getitem__(self, index):
 
         # doing this so that it is consistent with all other datasets
         # to return a PIL Image
-        # convert value to 8 bit unsigned integer
-        # color (white #255) the pixels
-        img = img.astype('uint8') * 255
         img = Image.fromarray(img, mode='L')
 
         if self.transform is not None: