我試圖在張量流中實(shí)現(xiàn)倒角距離.
但是,我的代碼將輸入視為numpy數(shù)組.要將numpy轉(zhuǎn)換為張量,我們需要運(yùn)行一個(gè)會(huì)話,但該過(guò)程已經(jīng)在另一個(gè)會(huì)話中.我認(rèn)為兩個(gè)會(huì)話不能并行運(yùn)行.
那么,任何人都可以幫我在tensorflow中實(shí)現(xiàn)倒角距離或幫助我解決這兩個(gè)同步會(huì)話的問(wèn)題嗎?
我的代碼是:
def chamfer_distance(array1,array2): # final = 0 # final = tf.cast(final,tf.float32) batch_size = array1.get_shape()[0].value num_point = array1.get_shape()[1].value sess = tf.Session() arr1,arr2 = sess.run([array1,array2]) del sess dist = 0 for i in range(batch_size): tree1 = KDTree(arr1[i], leafsize=num_point 1) tree2 = KDTree(arr2[i], leafsize=num_point 1) distances1, _ = tree1.query(arr2[i]) distances2, _ = tree2.query(arr1[i]) distances1 = tf.convert_to_tensor(distances1) distances2 = tf.convert_to_tensor(distances2) av_dist1 = tf.reduce_mean(distances1) av_dist2 = tf.reduce_mean(distances2) dist = dist (av_dist1 av_dist2)/batch_size return dist
解決方法:
我已經(jīng)實(shí)現(xiàn)了TF版倒角距離:
def distance_matrix(array1, array2): """ arguments: array1: the array, size: (num_point, num_feature) array2: the samples, size: (num_point, num_feature) returns: distances: each entry is the distance from a sample to array1 , it's size: (num_point, num_point) """ num_point, num_features = array1.shape expanded_array1 = tf.tile(array1, (num_point, 1)) expanded_array2 = tf.reshape( tf.tile(tf.expand_dims(array2, 1), (1, num_point, 1)), (-1, num_features)) distances = tf.norm(expanded_array1-expanded_array2, axis=1) distances = tf.reshape(distances, (num_point, num_point)) return distancesdef av_dist(array1, array2): """ arguments: array1, array2: both size: (num_points, num_feature) returns: distances: size: (1,) """ distances = distance_matrix(array1, array2) distances = tf.reduce_min(distances, axis=1) distances = tf.reduce_mean(distances) return distancesdef av_dist_sum(arrays): """ arguments: arrays: array1, array2 returns: sum of av_dist(array1, array2) and av_dist(array2, array1) """ array1, array2 = arrays av_dist1 = av_dist(array1, array2) av_dist2 = av_dist(array2, array1) return av_dist1 av_dist2def chamfer_distance_tf(array1, array2): batch_size, num_point, num_features = array1.shape dist = tf.reduce_mean( tf.map_fn(av_dist_sum, elems=(array1, array2), dtype=tf.float64) ) return dist
為了驗(yàn)證目的,我還實(shí)現(xiàn)了一個(gè)sklearn版本:
def chamfer_distance_sklearn(array1,array2): batch_size, num_point = array1.shape[:2] dist = 0 for i in range(batch_size): tree1 = KDTree(array1[i], leaf_size=num_point 1) tree2 = KDTree(array2[i], leaf_size=num_point 1) distances1, _ = tree1.query(array2[i]) distances2, _ = tree2.query(array1[i]) av_dist1 = np.mean(distances1) av_dist2 = np.mean(distances2) dist = dist (av_dist1 av_dist2)/batch_size return dist
也是一個(gè)numpy版本:
def array2samples_distance(array1, array2): """ arguments: array1: the array, size: (num_point, num_feature) array2: the samples, size: (num_point, num_feature) returns: distances: each entry is the distance from a sample to array1 """ num_point, num_features = array1.shape expanded_array1 = np.tile(array1, (num_point, 1)) expanded_array2 = np.reshape( np.tile(np.expand_dims(array2, 1), (1, num_point, 1)), (-1, num_features)) distances = LA.norm(expanded_array1-expanded_array2, axis=1) distances = np.reshape(distances, (num_point, num_point)) distances = np.min(distances, axis=1) distances = np.mean(distances) return distancesdef chamfer_distance_numpy(array1, array2): batch_size, num_point, num_features = array1.shape dist = 0 for i in range(batch_size): av_dist1 = array2samples_distance(array1[i], array2[i]) av_dist2 = array2samples_distance(array2[i], array1[i]) dist = dist (av_dist1 av_dist2)/batch_size return dist
您可以使用以下腳本驗(yàn)證結(jié)果:
batch_size = 8num_point = 20num_features = 4np.random.seed(1)array1 = np.random.randint(0, high=4, size=(batch_size, num_point, num_features))array2 = np.random.randint(0, high=4, size=(batch_size, num_point, num_features))print('sklearn: ', chamfer_distance_sklearn(array1, array2))print('numpy: ', chamfer_distance_numpy(array1, array2))array1_tf = tf.constant(array1, dtype=tf.float64)array2_tf = tf.constant(array2, dtype=tf.float64)dist_tf = chamfer_distance_tf(array1_tf, array2_tf)with tf.Session() as sess: print('tf: ', sess.run(dist_tf))
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