I'm getting the following error:

TypeError: Expected binary or unicode string, got [


I have several features that are histories of user activity. I am trying to predict whether a given user will take an action (represented by a 0 or 1 in my y_train list below) based off of their histories of different types of actions. For example, one feature might be button_A_click_per_day and the history for a given user would be a vector of button A clicks per day over the past 365 days.

The relevant snippets of my code is as follow:

import tensorflow as tf

# Build feature columns for classifier
feature_columns = []
for key in X_train:
    col = tf.feature_column.numeric_column(

# Build classifier
classifier = tf.estimator.DNNClassifier(
    hidden_units=[10, 10],

And X_train is structured as follows:

>>> X_train['<feature_name>']
129     [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, ...
1294    [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, ...
860     [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, ...
Name: <feature_name>, Length: 1377, dtype: object

My train input function is as follows:

def train_input_fn(features, labels, batch_size):
    dataset = tf.data.Dataset.from_tensor_slices((dict(features), labels))
    dataset = dataset.shuffle(buffer_size=1000).repeat(count=None).batch(batch_size)
    return dataset.make_one_shot_iterator().get_next()

Finally, when issuing the following command...

    # input_fn is a fn that takes not arguments and returns an iterator.
    input_fn=lambda: train_input_fn(X_train, y_train, batch_size=100),

I get the error:

~/.pyenv/versions/anaconda3-5.0.1/lib/python3.6/site-packages/tensorflow/python/util/compat.py in as_bytes(bytes_or_text, encoding)
     63   else:
     64     raise TypeError('Expected binary or unicode string, got %r' %
---> 65                     (bytes_or_text,))

TypeError: Expected binary or unicode string, got [0.0, 0.0, 0...


  1. Do you know what I'm doing wrong to get this error?
  2. Is there a better way to model features that are histories?
  • $\begingroup$ have you tried to specify the data type explicitly? $\endgroup$ – Media Feb 19 '18 at 15:40
  • $\begingroup$ I figured the default data type of tf.float32 would be correct since each item in the list is a float and since I used an integer max_width for shape. $\endgroup$ – Paul Feb 22 '18 at 0:14
  • $\begingroup$ So now your dtype is tf.float32 and still getting the same error? $\endgroup$ – Media Feb 22 '18 at 14:04
  • $\begingroup$ Correct. Still getting error. $\endgroup$ – Paul Feb 22 '18 at 20:46
  • 2
    $\begingroup$ did you get any solution.. I am also facing exactly the same issue. $\endgroup$ – maswadkar Jun 5 '18 at 7:50

You should use a built-in function for train_input_fn instead of writing your own. For example:

train_input_fn = tf.estimator.inputs.numpy_input_fn(
    x={"x": np.array(training_set.data)},

There is a complete example in the TensorFlow documentation here.

| improve this answer | |

For me, the cause was incorrect type decimal for some column; fixed by using instead float

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I have similar experience, solved by calling pd.Series#tolist() apparently. Here is a whole example.

import tensorflow as tf
import pandas as pd
def get_dataset():
    data = [['Tom', 'M', 95], ['Jerry', 'M', 96], ['Tonny', 'M', 97], ['Lisa', 'F', 98]]
    dataframe = pd.DataFrame(data=data, columns=['name', 'gender', 'score'])
    labels = dataframe.pop('score')
    features = dict()
    # call `pd.Series#tolist()` apparently
    for col_name in dataframe.columns:
        features[col_name] = dataframe[col_name].tolist()
    dataset = tf.data.Dataset.from_tensor_slices((features, labels))
    return dataset

features,labels = dataset.make_one_shot_iterator().get_next()

with tf.Session() as sess:
[({'name': array([b'Tom', b'Jerry'], dtype=object), 'gender': array([b'M', b'M'], dtype=object)}, array([95, 96], dtype=int64))]
[({'name': array([b'Tonny', b'Lisa'], dtype=object), 'gender': array([b'M', b'F'], dtype=object)}, array([97, 98], dtype=int64))]
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