_w2row() {
    const inputChannels = this.weights['kernel'].tensor.shape[2]
    const [nbFilter, nbRow, nbCol] = this.kernelShape
    const patchLen = nbRow * nbCol * inputChannels

    this.wRowsMat = new Tensor([], [patchLen, nbFilter])

    const patch = new Tensor([], [nbRow, nbCol, inputChannels])
    const patchRaveled = new Tensor([], [patchLen])
    for (let n = 0; n < nbFilter; n++) {
      ops.assign(patch.tensor, this.weights['kernel'].tensor.pick(null, null, null, n))
      patchRaveled.replaceTensorData(patch.tensor.data)
      ops.assign(this.wRowsMat.tensor.pick(null, n), patchRaveled.tensor)
    }

    return this.wRowsMat
  }
Convert filter weights to row matrix

@returns {Tensor}