Symbol API

    .. currentmodule:: mxnet.symbol

Overview

This document lists the routines of the symbolic expression package:

.. autosummary::
    :nosignatures:

    mxnet.symbol

The Symbol API, defined in the symbol (or simply sym) package, provides neural network graphs and auto-differentiation. A symbol represents a multi-output symbolic expression. They are composited by operators, such as simple matrix operations (e.g. “+”), or a neural network layer (e.g. convolution layer). An operator can take several input variables, produce more than one output variables, and have internal state variables. A variable can be either free, which we can bind with value later, or an output of another symbol.

>>> a = mx.sym.Variable('a')
>>> b = mx.sym.Variable('b')
>>> c = 2 * a + b
>>> type(c)
<class 'mxnet.symbol.Symbol'>
>>> e = c.bind(mx.cpu(), {'a': mx.nd.array([1,2]), 'b':mx.nd.array([2,3])})
>>> y = e.forward()
>>> y
[<NDArray 2 @cpu(0)>]
>>> y[0].asnumpy()
array([ 4.,  7.], dtype=float32)

A detailed tutorial is available at Symbol - Neural network graphs and auto-differentiation.

.. note:: most operators provided in ``symbol`` are similar to those in ``ndarray``
   although there are few differences:

   - ``symbol`` adopts declarative programming. In other words, we need to first
     compose the computations, and then feed it with data for execution whereas
     ndarray adopts imperative programming.

   - Most binary operators in ``symbol`` such as ``+`` and ``>`` don't broadcast.
     We need to call the broadcast version of the operator such as ``broadcast_plus``
     explicitly.

In the rest of this document, we first overview the methods provided by the symbol.Symbol class, and then list other routines provided by the symbol package.

The Symbol class

Composition

Composite multiple symbols into a new one by an operator.

.. autosummary::
    :nosignatures:

    Symbol.__call__

Arithmetic operations

.. autosummary::
    :nosignatures:

    Symbol.__add__
    Symbol.__sub__
    Symbol.__rsub__
    Symbol.__neg__
    Symbol.__mul__
    Symbol.__div__
    Symbol.__rdiv__
    Symbol.__mod__
    Symbol.__rmod__
    Symbol.__pow__

Trigonometric functions

.. autosummary::
    :nosignatures:

    Symbol.sin
    Symbol.cos
    Symbol.tan
    Symbol.arcsin
    Symbol.arccos
    Symbol.arctan
    Symbol.degrees
    Symbol.radians

Hyperbolic functions

.. autosummary::
    :nosignatures:

    Symbol.sinh
    Symbol.cosh
    Symbol.tanh
    Symbol.arcsinh
    Symbol.arccosh
    Symbol.arctanh

Exponents and logarithms

.. autosummary::
    :nosignatures:

    Symbol.exp
    Symbol.expm1
    Symbol.log
    Symbol.log10
    Symbol.log2
    Symbol.log1p

Powers

.. autosummary::
    :nosignatures:

    Symbol.sqrt
    Symbol.rsqrt
    Symbol.cbrt
    Symbol.rcbrt
    Symbol.square

Basic neural network functions

.. autosummary::
    :nosignatures:

    Symbol.relu
    Symbol.sigmoid
    Symbol.softmax
    Symbol.log_softmax

Comparison operators

.. autosummary::
    :nosignatures:

    Symbol.__lt__
    Symbol.__le__
    Symbol.__gt__
    Symbol.__ge__
    Symbol.__eq__
    Symbol.__ne__

Symbol creation

.. autosummary::
    :nosignatures:

    Symbol.zeros_like
    Symbol.ones_like
    Symbol.diag

Changing shape and type

.. autosummary::
    :nosignatures:

    Symbol.astype
    Symbol.shape_array
    Symbol.size_array
    Symbol.reshape
    Symbol.reshape_like
    Symbol.flatten
    Symbol.expand_dims

Expanding elements

.. autosummary::
    :nosignatures:

    Symbol.broadcast_to
    Symbol.broadcast_axes
    Symbol.broadcast_like
    Symbol.tile
    Symbol.pad

Rearranging elements

.. autosummary::
    :nosignatures:

    Symbol.transpose
    Symbol.swapaxes
    Symbol.flip
    Symbol.depth_to_space
    Symbol.space_to_depth

Reduce functions

.. autosummary::
    :nosignatures:

    Symbol.sum
    Symbol.nansum
    Symbol.prod
    Symbol.nanprod
    Symbol.mean
    Symbol.max
    Symbol.min
    Symbol.norm

Rounding

.. autosummary::
    :nosignatures:

    Symbol.round
    Symbol.rint
    Symbol.fix
    Symbol.floor
    Symbol.ceil
    Symbol.trunc

Sorting and searching

.. autosummary::
    :nosignatures:

    Symbol.sort
    Symbol.argsort
    Symbol.topk
    Symbol.argmax
    Symbol.argmin
    Symbol.argmax_channel

Query information

.. autosummary::
    :nosignatures:

    Symbol.name
    Symbol.list_arguments
    Symbol.list_outputs
    Symbol.list_auxiliary_states
    Symbol.list_attr
    Symbol.attr
    Symbol.attr_dict

Indexing

.. autosummary::
    :nosignatures:

    Symbol.slice
    Symbol.slice_axis
    Symbol.slice_like
    Symbol.take
    Symbol.one_hot
    Symbol.pick
    ravel_multi_index
    unravel_index

Get internal and output symbol

.. autosummary::
    :nosignatures:

    Symbol.__getitem__
    Symbol.__iter__
    Symbol.get_internals
    Symbol.get_children

Inference type and shape

.. autosummary::
    :nosignatures:

    Symbol.infer_type
    Symbol.infer_shape
    Symbol.infer_shape_partial

Bind

.. autosummary::
    :nosignatures:

    Symbol.bind
    Symbol.simple_bind

Save

.. autosummary::
    :nosignatures:

    Symbol.save
    Symbol.tojson
    Symbol.debug_str

Miscellaneous

.. autosummary::
    :nosignatures:

    Symbol.clip
    Symbol.sign

Symbol creation routines

.. autosummary::
    :nosignatures:

    var
    zeros
    zeros_like
    ones
    ones_like
    arange

Symbol manipulation routines

Changing shape and type

.. autosummary::
    :nosignatures:

    cast
    shape_array
    size_array
    reshape
    reshape_like
    flatten
    expand_dims
    diag

Expanding elements

.. autosummary::
    :nosignatures:

    broadcast_to
    broadcast_axes
    broadcast_like
    repeat
    tile
    pad

Rearranging elements

.. autosummary::
    :nosignatures:

    transpose
    swapaxes
    flip
    depth_to_space
    space_to_depth

Joining and splitting symbols

.. autosummary::
    :nosignatures:

    concat
    split
    stack

Indexing routines

.. autosummary::
    :nosignatures:

    slice
    slice_axis
    slice_like
    take
    batch_take
    one_hot
    pick
    where
    gather_nd
    scatter_nd

Mathematical functions

Arithmetic operations

.. autosummary::
    :nosignatures:

    broadcast_add
    broadcast_sub
    broadcast_mul
    broadcast_div
    broadcast_mod
    negative
    dot
    batch_dot
    add_n

Trigonometric functions

.. autosummary::
    :nosignatures:

    sin
    cos
    tan
    arcsin
    arccos
    arctan
    hypot
    broadcast_hypot
    degrees
    radians

Hyperbolic functions

.. autosummary::
    :nosignatures:

    sinh
    cosh
    tanh
    arcsinh
    arccosh
    arctanh

Reduce functions

.. autosummary::
    :nosignatures:

    sum
    nansum
    prod
    nanprod
    mean
    max
    min
    norm

Rounding

.. autosummary::
    :nosignatures:

    round
    rint
    fix
    floor
    ceil
    trunc

Exponents and logarithms

.. autosummary::
    :nosignatures:

    exp
    expm1
    log
    log10
    log2
    log1p

Powers

.. autosummary::
    :nosignatures:

    broadcast_power
    sqrt
    rsqrt
    cbrt
    rcbrt
    square
    reciprocal

Comparison

.. autosummary::
    :nosignatures:

    broadcast_equal
    broadcast_not_equal
    broadcast_greater
    broadcast_greater_equal
    broadcast_lesser
    broadcast_lesser_equal

Logical

.. autosummary::
    :nosignatures:

    broadcast_logical_and
    broadcast_logical_or
    broadcast_logical_xor
    logical_not

Random sampling

.. autosummary::
    :nosignatures:

    mxnet.symbol.random.uniform
    mxnet.symbol.random.normal
    mxnet.symbol.random.gamma
    mxnet.symbol.random.exponential
    mxnet.symbol.random.poisson
    mxnet.symbol.random.negative_binomial
    mxnet.symbol.random.generalized_negative_binomial
    mxnet.symbol.random.multinomial
    mxnet.symbol.random.shuffle
    mxnet.random.seed

Sorting and searching

.. autosummary::
    :nosignatures:

    sort
    topk
    argsort
    argmax
    argmin

Sequence operation

.. autosummary::
    :nosignatures:

    SequenceLast
    SequenceMask
    SequenceReverse

Miscellaneous

.. autosummary::
    :nosignatures:

    maximum
    minimum
    broadcast_maximum
    broadcast_minimum
    clip
    abs
    sign
    gamma
    gammaln

Neural network

Basic

.. autosummary::
    :nosignatures:

    FullyConnected
    Convolution
    Activation
    BatchNorm
    Pooling
    SoftmaxOutput
    softmax
    log_softmax
    relu
    sigmoid
    erf

More

.. autosummary::
    :nosignatures:

    Correlation
    Deconvolution
    RNN
    Embedding
    LeakyReLU
    InstanceNorm
    LayerNorm
    L2Normalization
    LRN
    ROIPooling
    SoftmaxActivation
    Dropout
    BilinearSampler
    GridGenerator
    UpSampling
    SpatialTransformer
    LinearRegressionOutput
    LogisticRegressionOutput
    MAERegressionOutput
    SVMOutput
    softmax_cross_entropy
    smooth_l1
    IdentityAttachKLSparseReg
    MakeLoss
    BlockGrad
    Custom

API Reference

.. autoclass:: mxnet.symbol.Symbol
    :members:
    :special-members:

.. automodule:: mxnet.symbol
    :members:
    :imported-members:
    :special-members:
    :exclude-members: Symbol

.. automodule:: mxnet.symbol.random
    :members: