`Input`

function```
tf.keras.Input(
shape=None,
batch_size=None,
name=None,
dtype=None,
sparse=None,
tensor=None,
ragged=None,
type_spec=None,
**kwargs
)
```

`Input()`

is used to instantiate a Keras tensor.

A Keras tensor is a symbolic tensor-like object, which we augment with certain attributes that allow us to build a Keras model just by knowing the inputs and outputs of the model.

For instance, if `a`

, `b`

and `c`

are Keras tensors,
it becomes possible to do:
`model = Model(input=[a, b], output=c)`

**Arguments**

**shape**: A shape tuple (integers), not including the batch size. For instance,`shape=(32,)`

indicates that the expected input will be batches of 32-dimensional vectors. Elements of this tuple can be None; 'None' elements represent dimensions where the shape is not known.**batch_size**: optional static batch size (integer).**name**: An optional name string for the layer. Should be unique in a model (do not reuse the same name twice). It will be autogenerated if it isn't provided.**dtype**: The data type expected by the input, as a string (`float32`

,`float64`

,`int32`

...)**sparse**: A boolean specifying whether the placeholder to be created is sparse. Only one of 'ragged' and 'sparse' can be True. Note that, if`sparse`

is False, sparse tensors can still be passed into the input - they will be densified with a default value of 0.**tensor**: Optional existing tensor to wrap into the`Input`

layer. If set, the layer will use the`tf.TypeSpec`

of this tensor rather than creating a new placeholder tensor.**ragged**: A boolean specifying whether the placeholder to be created is ragged. Only one of 'ragged' and 'sparse' can be True. In this case, values of 'None' in the 'shape' argument represent ragged dimensions. For more information about RaggedTensors, see this guide.**type_spec**: A`tf.TypeSpec`

object to create the input placeholder from. When provided, all other args except name must be None.****kwargs**: deprecated arguments support. Supports`batch_shape`

and`batch_input_shape`

.

**Returns**

A `tensor`

.

**Example**

```
# this is a logistic regression in Keras
x = Input(shape=(32,))
y = Dense(16, activation='softmax')(x)
model = Model(x, y)
```

Note that even if eager execution is enabled,
`Input`

produces a symbolic tensor-like object (i.e. a placeholder).
This symbolic tensor-like object can be used with lower-level
TensorFlow ops that take tensors as inputs, as such:

```
x = Input(shape=(32,))
y = tf.square(x) # This op will be treated like a layer
model = Model(x, y)
```

(This behavior does not work for higher-order TensorFlow APIs such as
control flow and being directly watched by a `tf.GradientTape`

).

However, the resulting model will not track any variables that were used as inputs to TensorFlow ops. All variable usages must happen within Keras layers to make sure they will be tracked by the model's weights.

The Keras Input can also create a placeholder from an arbitrary `tf.TypeSpec`

,
e.g:

```
x = Input(type_spec=tf.RaggedTensorSpec(shape=[None, None],
dtype=tf.float32, ragged_rank=1))
y = x.values
model = Model(x, y)
```

When passing an arbitrary `tf.TypeSpec`

, it must represent the signature of an
entire batch instead of just one example.

**Raises**

**ValueError**: If both`sparse`

and`ragged`

are provided.**ValueError**: If both`shape`

and (`batch_input_shape`

or`batch_shape`

) are provided.**ValueError**: If`shape`

,`tensor`

and`type_spec`

are None.**ValueError**: If arguments besides`type_spec`

are non-None while`type_spec`

is passed.**ValueError**: if any unrecognized parameters are provided.