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[TensorFolow]函数: tf.nn.conv2d

[TensorFolow]函数: tf.nn.conv2d

作者: HighCool_ | 来源:发表于2017-11-10 13:07 被阅读0次
      def conv2d(input, filter, strides, padding, use_cudnn_on_gpu=True, data_format="NHWC", name=None):
    

    r"""Computes a 2-D convolution given 4-D input and filter tensors.

    Given an input tensor of shape [batch, in_height, in_width, in_channels]
    and a filter / kernel tensor of shape
    [filter_height, filter_width, in_channels, out_channels], this op
    performs the following:

    1. Flattens the filter to a 2-D matrix with shape
      [filter_height * filter_width * in_channels, output_channels].
    2. Extracts image patches from the input tensor to form a virtual
      tensor of shape [batch, out_height, out_width, filter_height * filter_width * in_channels].
    3. For each patch, right-multiplies the filter matrix and the image patch
      vector.

    In detail, with the default NHWC format,

      output[b, i, j, k] =
          sum_{di, dj, q} input[b, strides[1] * i + di, strides[2] * j + dj, q] *
                          filter[di, dj, q, k]
    

    Must have strides[0] = strides[3] = 1. For the most common case of the same
    horizontal and vertices strides, strides = [1, stride, stride, 1].

    Args:
    input: A Tensor. Must be one of the following types: half, float32.
    A 4-D tensor. The dimension order is interpreted according to the value
    of data_format, see below for details.
    filter: A Tensor. Must have the same type as input.
    A 4-D tensor of shape
    [filter_height, filter_width, in_channels, out_channels]
    strides: A list of ints.
    1-D tensor of length 4. The stride of the sliding window for each
    dimension of input. The dimension order is determined by the value of
    data_format, see below for details.
    padding: A string from: "SAME", "VALID".
    The type of padding algorithm to use.
    use_cudnn_on_gpu: An optional bool. Defaults to True.
    data_format: An optional string from: "NHWC", "NCHW". Defaults to "NHWC".
    Specify the data format of the input and output data. With the
    default format "NHWC", the data is stored in the order of:
    [batch, height, width, channels].
    Alternatively, the format could be "NCHW", the data storage order of:
    [batch, channels, height, width].
    name: A name for the operation (optional).

    Returns:
    A Tensor. Has the same type as input.
    A 4-D tensor. The dimension order is determined by the value of
    data_format, see below for details.
    """

      if not isinstance(strides, (list, tuple)):
        raise TypeError(
            "Expected list for 'strides' argument to "
            "'conv2d' Op, not %r." % strides)
      strides = [_execute.make_int(_i, "strides") for _i in strides]
      padding = _execute.make_str(padding, "padding")
      if use_cudnn_on_gpu is None:
        use_cudnn_on_gpu = True
      use_cudnn_on_gpu = _execute.make_bool(use_cudnn_on_gpu, "use_cudnn_on_gpu")
      if data_format is None:
        data_format = "NHWC"
      data_format = _execute.make_str(data_format, "data_format")
      _ctx = _context.context()
      if _ctx.in_graph_mode():
        _, _, _op = _op_def_lib._apply_op_helper(
            "Conv2D", input=input, filter=filter, strides=strides,
            padding=padding, use_cudnn_on_gpu=use_cudnn_on_gpu,
            data_format=data_format, name=name)
        _result = _op.outputs[:]
        _inputs_flat = _op.inputs
        _attrs = ("T", _op.get_attr("T"), "strides", _op.get_attr("strides"),
                  "use_cudnn_on_gpu", _op.get_attr("use_cudnn_on_gpu"), "padding",
                  _op.get_attr("padding"), "data_format",
                  _op.get_attr("data_format"))
      else:
        _attr_T, _inputs_T = _execute.args_to_matching_eager([input, filter], _ctx)
        (input, filter) = _inputs_T
        _attr_T = _attr_T.as_datatype_enum
        _inputs_flat = [input, filter]
        _attrs = ("T", _attr_T, "strides", strides, "use_cudnn_on_gpu",
                  use_cudnn_on_gpu, "padding", padding, "data_format",
                  data_format)
        _result = _execute.execute(b"Conv2D", 1, inputs=_inputs_flat,
                                   attrs=_attrs, ctx=_ctx, name=name)
      _execute.record_gradient(
          "Conv2D", _inputs_flat, _attrs, _result, name)
      _result, = _result
      return _result
    

    注意函数的几个参数
    每个参数的shape均不相同
    最终返回Returns:
    A Tensor. Has the same type as input.

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