How to convert string labels to one-hot vectors in TensorFlow?
Solution 1
It's been more than 2 years since this question was asked, but this answer might still be relevant for some. Here's one simple way to transform string labels into one-hot vectors in TF:
import tensorflow as tf
vocab = ['a', 'b', 'c']
input = tf.placeholder(dtype=tf.string, shape=(None,))
matches = tf.stack([tf.equal(input, s) for s in vocab], axis=-1)
onehot = tf.cast(matches, tf.float32)
with tf.Session() as sess:
out = sess.run(onehot, feed_dict={input: ['c', 'a']})
print(out) # prints [[0. 0. 1.]
# [1. 0. 0.]]
Solution 2
You may want to try to feed your index
variable into a placeholder, which, in turn gets transformed into a one-hot vector via tf.one_hot
? Something along these lines:
lbl = tf.placeholder(tf.uint8, [YOUR_BATCH_SIZE])
lbl_one_hot = tf.one_hot(lbl, YOUR_VOCAB_SIZE, 1.0, 0.0)
lb_h = sess.run([lbl_one_hot], feed_dict={lbl: index})
Not sure if you are doing things in batches, so if not in your case YOUR_BATCH_SIZE might be irrelevant. You can also do it using numpy.zeros, but I find the above cleaner and easier, especially with batching.
Admin
Updated on June 14, 2022Comments
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Admin almost 2 years
I'm new to TensorFlow and would like to read a comma separated values (csv) file, containing 2 columns, column 1 the index, and column 2 a label string. I have the following code which reads lines in the csv file line by line and I am able to get the data in the csv file correctly using print statements. However, I would like to do one-hot encoding conversion from the string labels and do not how to do it in TensorFlow. The final goal is to use the tf.train.batch() function so I can get batches of one-hot label vectors to train a neural network.
As you can see in the code below, I can create a one-hot vector for each of the label entries manually within a TensorFlow session. But how do I use the tf.train.batch() function? If I move the line
label_batch = tf.train.batch([col2], batch_size=5)
into the TensorFlow session block (replacing col2 with label_one_hot), the program blocks doing nothing. I tried to move the one-hot vector conversion outside the TensorFlow session but I failed to get it to work correctly. What is the correct way to do it? Please help.
label_files = [] label_files.append(LABEL_FILE) print "label_files: ", label_files filename_queue = tf.train.string_input_producer(label_files) reader = tf.TextLineReader() key, value = reader.read(filename_queue) print "key:", key, ", value:", value record_defaults = [['default_id'], ['default_label']] col1, col2 = tf.decode_csv(value, record_defaults=record_defaults) num_lines = sum(1 for line in open(LABEL_FILE)) label_batch = tf.train.batch([col2], batch_size=5) with tf.Session() as sess: coordinator = tf.train.Coordinator() threads = tf.train.start_queue_runners(coord=coordinator) for i in range(100): column1, column2 = sess.run([col1, col2]) index = 0 if column2 == 'airplane': index = 0 elif column2 == 'automobile': index = 1 elif column2 == 'bird': index = 2 elif column2 == 'cat': index = 3 elif column2 == 'deer': index = 4 elif column2 == 'dog': index = 5 elif column2 == 'frog': index = 6 elif column2 == 'horse': index = 7 elif column2 == 'ship': index = 8 elif column2 == 'truck': index = 9 label_one_hot = tf.one_hot([index], 10) # depth=10 for 10 categories print "column1:", column1, ", column2:", column2 # print "onehot label:", sess.run([label_one_hot]) print sess.run(label_batch) coordinator.request_stop() coordinator.join(threads)