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lab_1/scripts/data_utils.py

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+from __future__ import print_function
+
+from builtins import range
+from six.moves import cPickle as pickle
+import numpy as np
+import os
+from imageio import imread
+import platform
+
+def load_pickle(f):
+    version = platform.python_version_tuple()
+    if version[0] == '2':
+        return  pickle.load(f)
+    elif version[0] == '3':
+        return  pickle.load(f, encoding='latin1')
+    raise ValueError("invalid python version: {}".format(version))
+
+def load_CIFAR_batch(filename):
+    """ load single batch of cifar """
+    with open(filename, 'rb') as f:
+        datadict = load_pickle(f)
+        X = datadict['data']
+        Y = datadict['labels']
+        X = X.reshape(10000, 3, 32, 32).transpose(0,2,3,1).astype("float")
+        Y = np.array(Y)
+        return X, Y
+
+def load_CIFAR10(ROOT):
+    """ load all of cifar """
+    xs = []
+    ys = []
+    for b in range(1,6):
+        f = os.path.join(ROOT, 'data_batch_%d' % (b, ))
+        X, Y = load_CIFAR_batch(f)
+        xs.append(X)
+        ys.append(Y)
+    Xtr = np.concatenate(xs)
+    Ytr = np.concatenate(ys)
+    del X, Y
+    Xte, Yte = load_CIFAR_batch(os.path.join(ROOT, 'test_batch'))
+    return Xtr, Ytr, Xte, Yte
+
+
+def get_CIFAR10_data(num_training=49000, num_validation=1000, num_test=1000,
+                     subtract_mean=True):
+    """
+    Load the CIFAR-10 dataset from disk and perform preprocessing to prepare
+    it for classifiers. These are the same steps as we used for the SVM, but
+    condensed to a single function.
+    """
+    # Load the raw CIFAR-10 data
+    cifar10_dir = 'cs231n/datasets/cifar-10-batches-py'
+    X_train, y_train, X_test, y_test = load_CIFAR10(cifar10_dir)
+
+    # Subsample the data
+    mask = list(range(num_training, num_training + num_validation))
+    X_val = X_train[mask]
+    y_val = y_train[mask]
+    mask = list(range(num_training))
+    X_train = X_train[mask]
+    y_train = y_train[mask]
+    mask = list(range(num_test))
+    X_test = X_test[mask]
+    y_test = y_test[mask]
+
+    # Normalize the data: subtract the mean image
+    if subtract_mean:
+        mean_image = np.mean(X_train, axis=0)
+        X_train -= mean_image
+        X_val -= mean_image
+        X_test -= mean_image
+
+    # Transpose so that channels come first
+    X_train = X_train.transpose(0, 3, 1, 2).copy()
+    X_val = X_val.transpose(0, 3, 1, 2).copy()
+    X_test = X_test.transpose(0, 3, 1, 2).copy()
+
+    # Package data into a dictionary
+    return {
+      'X_train': X_train, 'y_train': y_train,
+      'X_val': X_val, 'y_val': y_val,
+      'X_test': X_test, 'y_test': y_test,
+    }
+
+
+def load_tiny_imagenet(path, dtype=np.float32, subtract_mean=True):
+    """
+    Load TinyImageNet. Each of TinyImageNet-100-A, TinyImageNet-100-B, and
+    TinyImageNet-200 have the same directory structure, so this can be used
+    to load any of them.
+
+    Inputs:
+    - path: String giving path to the directory to load.
+    - dtype: numpy datatype used to load the data.
+    - subtract_mean: Whether to subtract the mean training image.
+
+    Returns: A dictionary with the following entries:
+    - class_names: A list where class_names[i] is a list of strings giving the
+      WordNet names for class i in the loaded dataset.
+    - X_train: (N_tr, 3, 64, 64) array of training images
+    - y_train: (N_tr,) array of training labels
+    - X_val: (N_val, 3, 64, 64) array of validation images
+    - y_val: (N_val,) array of validation labels
+    - X_test: (N_test, 3, 64, 64) array of testing images.
+    - y_test: (N_test,) array of test labels; if test labels are not available
+      (such as in student code) then y_test will be None.
+    - mean_image: (3, 64, 64) array giving mean training image
+    """
+    # First load wnids
+    with open(os.path.join(path, 'wnids.txt'), 'r') as f:
+        wnids = [x.strip() for x in f]
+
+    # Map wnids to integer labels
+    wnid_to_label = {wnid: i for i, wnid in enumerate(wnids)}
+
+    # Use words.txt to get names for each class
+    with open(os.path.join(path, 'words.txt'), 'r') as f:
+        wnid_to_words = dict(line.split('\t') for line in f)
+        for wnid, words in wnid_to_words.items():
+            wnid_to_words[wnid] = [w.strip() for w in words.split(',')]
+    class_names = [wnid_to_words[wnid] for wnid in wnids]
+
+    # Next load training data.
+    X_train = []
+    y_train = []
+    for i, wnid in enumerate(wnids):
+        if (i + 1) % 20 == 0:
+            print('loading training data for synset %d / %d'
+                  % (i + 1, len(wnids)))
+        # To figure out the filenames we need to open the boxes file
+        boxes_file = os.path.join(path, 'train', wnid, '%s_boxes.txt' % wnid)
+        with open(boxes_file, 'r') as f:
+            filenames = [x.split('\t')[0] for x in f]
+        num_images = len(filenames)
+
+        X_train_block = np.zeros((num_images, 3, 64, 64), dtype=dtype)
+        y_train_block = wnid_to_label[wnid] * \
+                        np.ones(num_images, dtype=np.int64)
+        for j, img_file in enumerate(filenames):
+            img_file = os.path.join(path, 'train', wnid, 'images', img_file)
+            img = imread(img_file)
+            if img.ndim == 2:
+        ## grayscale file
+                img.shape = (64, 64, 1)
+            X_train_block[j] = img.transpose(2, 0, 1)
+        X_train.append(X_train_block)
+        y_train.append(y_train_block)
+
+    # We need to concatenate all training data
+    X_train = np.concatenate(X_train, axis=0)
+    y_train = np.concatenate(y_train, axis=0)
+
+    # Next load validation data
+    with open(os.path.join(path, 'val', 'val_annotations.txt'), 'r') as f:
+        img_files = []
+        val_wnids = []
+        for line in f:
+            img_file, wnid = line.split('\t')[:2]
+            img_files.append(img_file)
+            val_wnids.append(wnid)
+        num_val = len(img_files)
+        y_val = np.array([wnid_to_label[wnid] for wnid in val_wnids])
+        X_val = np.zeros((num_val, 3, 64, 64), dtype=dtype)
+        for i, img_file in enumerate(img_files):
+            img_file = os.path.join(path, 'val', 'images', img_file)
+            img = imread(img_file)
+            if img.ndim == 2:
+                img.shape = (64, 64, 1)
+            X_val[i] = img.transpose(2, 0, 1)
+
+    # Next load test images
+    # Students won't have test labels, so we need to iterate over files in the
+    # images directory.
+    img_files = os.listdir(os.path.join(path, 'test', 'images'))
+    X_test = np.zeros((len(img_files), 3, 64, 64), dtype=dtype)
+    for i, img_file in enumerate(img_files):
+        img_file = os.path.join(path, 'test', 'images', img_file)
+        img = imread(img_file)
+        if img.ndim == 2:
+            img.shape = (64, 64, 1)
+        X_test[i] = img.transpose(2, 0, 1)
+
+    y_test = None
+    y_test_file = os.path.join(path, 'test', 'test_annotations.txt')
+    if os.path.isfile(y_test_file):
+        with open(y_test_file, 'r') as f:
+            img_file_to_wnid = {}
+            for line in f:
+                line = line.split('\t')
+                img_file_to_wnid[line[0]] = line[1]
+        y_test = [wnid_to_label[img_file_to_wnid[img_file]]
+                  for img_file in img_files]
+        y_test = np.array(y_test)
+
+    mean_image = X_train.mean(axis=0)
+    if subtract_mean:
+        X_train -= mean_image[None]
+        X_val -= mean_image[None]
+        X_test -= mean_image[None]
+
+    return {
+      'class_names': class_names,
+      'X_train': X_train,
+      'y_train': y_train,
+      'X_val': X_val,
+      'y_val': y_val,
+      'X_test': X_test,
+      'y_test': y_test,
+      'class_names': class_names,
+      'mean_image': mean_image,
+    }
+
+
+def load_models(models_dir):
+    """
+    Load saved models from disk. This will attempt to unpickle all files in a
+    directory; any files that give errors on unpickling (such as README.txt)
+    will be skipped.
+
+    Inputs:
+    - models_dir: String giving the path to a directory containing model files.
+      Each model file is a pickled dictionary with a 'model' field.
+
+    Returns:
+    A dictionary mapping model file names to models.
+    """
+    models = {}
+    for model_file in os.listdir(models_dir):
+        with open(os.path.join(models_dir, model_file), 'rb') as f:
+            try:
+                models[model_file] = load_pickle(f)['model']
+            except pickle.UnpicklingError:
+                continue
+    return models
+
+
+def load_imagenet_val(num=None):
+    """Load a handful of validation images from ImageNet.
+
+    Inputs:
+    - num: Number of images to load (max of 25)
+
+    Returns:
+    - X: numpy array with shape [num, 224, 224, 3]
+    - y: numpy array of integer image labels, shape [num]
+    - class_names: dict mapping integer label to class name
+    """
+    imagenet_fn = 'cs231n/datasets/imagenet_val_25.npz'
+    if not os.path.isfile(imagenet_fn):
+      print('file %s not found' % imagenet_fn)
+      print('Run the following:')
+      print('cd cs231n/datasets')
+      print('bash get_imagenet_val.sh')
+      assert False, 'Need to download imagenet_val_25.npz'
+    f = np.load(imagenet_fn)
+    X = f['X']
+    y = f['y']
+    class_names = f['label_map'].item()
+    if num is not None:
+        X = X[:num]
+        y = y[:num]
+    return X, y, class_names

lab_1/scripts/gradient_check.py

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+from __future__ import print_function
+from builtins import range
+from past.builtins import xrange
+
+import numpy as np
+from random import randrange
+
+def eval_numerical_gradient(f, x, verbose=True, h=0.00001):
+    """
+    a naive implementation of numerical gradient of f at x
+    - f should be a function that takes a single argument
+    - x is the point (numpy array) to evaluate the gradient at
+    """
+
+    fx = f(x) # evaluate function value at original point
+    grad = np.zeros_like(x)
+    # iterate over all indexes in x
+    it = np.nditer(x, flags=['multi_index'], op_flags=['readwrite'])
+    while not it.finished:
+
+        # evaluate function at x+h
+        ix = it.multi_index
+        oldval = x[ix]
+        x[ix] = oldval + h # increment by h
+        fxph = f(x) # evalute f(x + h)
+        x[ix] = oldval - h
+        fxmh = f(x) # evaluate f(x - h)
+        x[ix] = oldval # restore
+
+        # compute the partial derivative with centered formula
+        grad[ix] = (fxph - fxmh) / (2 * h) # the slope
+        if verbose:
+            print(ix, grad[ix])
+        it.iternext() # step to next dimension
+
+    return grad
+
+
+def eval_numerical_gradient_array(f, x, df, h=1e-5):
+    """
+    Evaluate a numeric gradient for a function that accepts a numpy
+    array and returns a numpy array.
+    """
+    grad = np.zeros_like(x)
+    it = np.nditer(x, flags=['multi_index'], op_flags=['readwrite'])
+    while not it.finished:
+        ix = it.multi_index
+
+        oldval = x[ix]
+        x[ix] = oldval + h
+        pos = f(x).copy()
+        x[ix] = oldval - h
+        neg = f(x).copy()
+        x[ix] = oldval
+
+        grad[ix] = np.sum((pos - neg) * df) / (2 * h)
+        it.iternext()
+    return grad
+
+
+def eval_numerical_gradient_blobs(f, inputs, output, h=1e-5):
+    """
+    Compute numeric gradients for a function that operates on input
+    and output blobs.
+
+    We assume that f accepts several input blobs as arguments, followed by a
+    blob where outputs will be written. For example, f might be called like:
+
+    f(x, w, out)
+
+    where x and w are input Blobs, and the result of f will be written to out.
+
+    Inputs:
+    - f: function
+    - inputs: tuple of input blobs
+    - output: output blob
+    - h: step size
+    """
+    numeric_diffs = []
+    for input_blob in inputs:
+        diff = np.zeros_like(input_blob.diffs)
+        it = np.nditer(input_blob.vals, flags=['multi_index'],
+                       op_flags=['readwrite'])
+        while not it.finished:
+            idx = it.multi_index
+            orig = input_blob.vals[idx]
+
+            input_blob.vals[idx] = orig + h
+            f(*(inputs + (output,)))
+            pos = np.copy(output.vals)
+            input_blob.vals[idx] = orig - h
+            f(*(inputs + (output,)))
+            neg = np.copy(output.vals)
+            input_blob.vals[idx] = orig
+
+            diff[idx] = np.sum((pos - neg) * output.diffs) / (2.0 * h)
+
+            it.iternext()
+        numeric_diffs.append(diff)
+    return numeric_diffs
+
+
+def eval_numerical_gradient_net(net, inputs, output, h=1e-5):
+    return eval_numerical_gradient_blobs(lambda *args: net.forward(),
+                inputs, output, h=h)
+
+
+def grad_check_sparse(f, x, analytic_grad, num_checks=10, h=1e-5):
+    """
+    sample a few random elements and only return numerical
+    in this dimensions.
+    """
+
+    for i in range(num_checks):
+        ix = tuple([randrange(m) for m in x.shape])
+
+        oldval = x[ix]
+        x[ix] = oldval + h # increment by h
+        fxph = f(x) # evaluate f(x + h)
+        x[ix] = oldval - h # increment by h
+        fxmh = f(x) # evaluate f(x - h)
+        x[ix] = oldval # reset
+
+        grad_numerical = (fxph - fxmh) / (2 * h)
+        grad_analytic = analytic_grad[ix]
+        rel_error = (abs(grad_numerical - grad_analytic) /
+                    (abs(grad_numerical) + abs(grad_analytic)))
+        print('numerical: %f analytic: %f, relative error: %e'
+              %(grad_numerical, grad_analytic, rel_error))

lab_1/scripts/vis_utils.py

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+from builtins import range
+from past.builtins import xrange
+
+from math import sqrt, ceil
+import numpy as np
+
+def visualize_grid(Xs, ubound=255.0, padding=1):
+    """
+    Reshape a 4D tensor of image data to a grid for easy visualization.
+
+    Inputs:
+    - Xs: Data of shape (N, H, W, C)
+    - ubound: Output grid will have values scaled to the range [0, ubound]
+    - padding: The number of blank pixels between elements of the grid
+    """
+    (N, H, W, C) = Xs.shape
+    grid_size = int(ceil(sqrt(N)))
+    grid_height = H * grid_size + padding * (grid_size - 1)
+    grid_width = W * grid_size + padding * (grid_size - 1)
+    grid = np.zeros((grid_height, grid_width, C))
+    next_idx = 0
+    y0, y1 = 0, H
+    for y in range(grid_size):
+        x0, x1 = 0, W
+        for x in range(grid_size):
+            if next_idx < N:
+                img = Xs[next_idx]
+                low, high = np.min(img), np.max(img)
+                grid[y0:y1, x0:x1] = ubound * (img - low) / (high - low)
+                # grid[y0:y1, x0:x1] = Xs[next_idx]
+                next_idx += 1
+            x0 += W + padding
+            x1 += W + padding
+        y0 += H + padding
+        y1 += H + padding
+    # grid_max = np.max(grid)
+    # grid_min = np.min(grid)
+    # grid = ubound * (grid - grid_min) / (grid_max - grid_min)
+    return grid
+
+def vis_grid(Xs):
+    """ visualize a grid of images """
+    (N, H, W, C) = Xs.shape
+    A = int(ceil(sqrt(N)))
+    G = np.ones((A*H+A, A*W+A, C), Xs.dtype)
+    G *= np.min(Xs)
+    n = 0
+    for y in range(A):
+        for x in range(A):
+            if n < N:
+                G[y*H+y:(y+1)*H+y, x*W+x:(x+1)*W+x, :] = Xs[n,:,:,:]
+                n += 1
+    # normalize to [0,1]
+    maxg = G.max()
+    ming = G.min()
+    G = (G - ming)/(maxg-ming)
+    return G
+
+def vis_nn(rows):
+    """ visualize array of arrays of images """
+    N = len(rows)
+    D = len(rows[0])
+    H,W,C = rows[0][0].shape
+    Xs = rows[0][0]
+    G = np.ones((N*H+N, D*W+D, C), Xs.dtype)
+    for y in range(N):
+        for x in range(D):
+            G[y*H+y:(y+1)*H+y, x*W+x:(x+1)*W+x, :] = rows[y][x]
+    # normalize to [0,1]
+    maxg = G.max()
+    ming = G.min()
+    G = (G - ming)/(maxg-ming)
+    return G