# tf.keras.backend.concatenate

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|---|---|
| [![](https://www.tensorflow.org/images/tf_logo_32px.png) TensorFlow 1 version](https://www.tensorflow.org/versions/r1.15/api_docs/python/tf/keras/backend/concatenate) | [![](https://www.tensorflow.org/images/GitHub-Mark-32px.png) View source on GitHub](https://github.com/tensorflow/tensorflow/blob/v2.2.0/tensorflow/python/keras/backend.py#L2675-L2709) |

Concatenates a list of tensors alongside the specified axis.

#### View aliases


**Compat aliases for migration**

See
[Migration guide](https://www.tensorflow.org/guide/migrate) for
more details.

[`tf.compat.v1.keras.backend.concatenate`](https://www.tensorflow.org/api_docs/python/tf/keras/backend/concatenate)

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    tf.keras.backend.concatenate(
        tensors, axis=-1
    )

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| ## Arguments ||
|---|---|
| `tensors` | list of tensors to concatenate. |
| `axis` | concatenation axis. |

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| ## Returns ||
|---|---|
| A tensor. ||

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#### Example:

    a = tf.constant([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
    b = tf.constant([[10, 20, 30], [40, 50, 60], [70, 80, 90]])
    tf.keras.backend.concatenate((a, b), axis=-1)
    <tf.Tensor: shape=(3, 6), dtype=int32, numpy=
    array([[ 1,  2,  3, 10, 20, 30],
           [ 4,  5,  6, 40, 50, 60],
           [ 7,  8,  9, 70, 80, 90]], dtype=int32)>