TensorFlow 1 version

Converts each string in the input Tensor to its hash mod by a number of buckets.

    input, num_buckets, key, name=None

The hash function is deterministic on the content of the string within the process. The hash function is a keyed hash function, where attribute key defines the key of the hash function. key is an array of 2 elements.

A strong hash is important when inputs may be malicious, e.g. URLs with additional components. Adversaries could try to make their inputs hash to the same bucket for a denial-of-service attack or to skew the results. A strong hash can be used to make it difficult to find inputs with a skewed hash value distribution over buckets. This requires that the hash function is seeded by a high-entropy (random) "key" unknown to the adversary.

The additional robustness comes at a cost of roughly 4x higher compute time than tf.string_to_hash_bucket_fast.


tf.strings.to_hash_bucket_strong(["Hello", "TF"], 3, [1, 2]).numpy() 
array([2, 0]) 


  • input: A Tensor of type string. The strings to assign a hash bucket.
  • num_buckets: An int that is >= 1. The number of buckets.
  • key: A list of ints. The key used to seed the hash function, passed as a list of two uint64 elements.
  • name: A name for the operation (optional).


A Tensor of type int64.