tf.keras.backend.placeholder

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Instantiates a placeholder tensor and returns it.

Aliases:

• tf.compat.v1.keras.backend.placeholder
• tf.compat.v2.keras.backend.placeholder

tf.keras.backend.placeholder(
    shape=None,
    ndim=None,
    dtype=None,
    sparse=False,
    name=None,
    ragged=False
)

Arguments:

• shape: Shape of the placeholder (integer tuple, may include None entries).
• ndim: Number of axes of the tensor. At least one of {shape, ndim} must be specified. If both are specified, shape is used.
• dtype: Placeholder type.
• sparse: Boolean, whether the placeholder should have a sparse type.
• name: Optional name string for the placeholder.
• ragged: Boolean, whether the placeholder should have a ragged type. In this case, values of 'None' in the 'shape' argument represent ragged dimensions. For more information about RaggedTensors, see this guide.

Raises:

• ValueError: If called with eager execution
• ValueError: If called with sparse = True and ragged = True.

Returns:

Tensor instance (with Keras metadata included).

Examples:

>>> from keras import backend as K
>>> input_ph = K.placeholder(shape=(2, 4, 5))
>>> input_ph
<tf.Tensor 'Placeholder_4:0' shape=(2, 4, 5) dtype=float32>