我不是官方人员，可以试试这样：

assert isinstance(a, paddle.fluid.LodTensor)
assert isinstance(b, paddle.fluid.LodTensor)

return fluid.layers.elementwise_mul(
           a,
           fluid.layers.logical_not(b)
     )

@parap1uie-s 谢谢，我现在也是通过这种方式解决的

感谢解答。 @parap1uie-s

@gavin1332
我把如下numpy代码改成paddle

# numpy

conf[best_truth_overlap < neg_thresh] =  0

# paddle

conf = fluid.layers.elementwise_mul(
            conf,
            fluid.layers.cast(best_truth_overlap > neg_thresh, 'int32')
        )

结果报错了

W0331 13:53:30.755509  6610 operator.cc:181] cast raises an exception thrust::system::system_error, parallel_for failed: invalid configuration argument
F0331 13:53:30.755676  6610 exception_holder.h:37] std::exception caught, parallel_for failed: invalid configuration argument

***Check failure stack trace:***

W0331 13:53:30.757980  6609 operator.cc:181] elementwise_add raises an exception thrust::system::system_error, parallel_for failed: invalid configuration argument
F0331 13:53:30.758033  6609 exception_holder.h:37] std::exception caught, parallel_for failed: invalid configuration argument

***Check failure stack trace:***

    @     0x7f562c55ffed  google::LogMessage::Fail()
    @     0x7f562c55ffed  google::LogMessage::Fail()
    @     0x7f562c563a9c  google::LogMessage::SendToLog()
    @     0x7f562c563a9c  google::LogMessage::SendToLog()
    @     0x7f562c55fb13  google::LogMessage::Flush()
    @     0x7f562c55fb13  google::LogMessage::Flush()
    @     0x7f562c564fae  google::LogMessageFatal::~LogMessageFatal()
    @     0x7f562c564fae  google::LogMessageFatal::~LogMessageFatal()
    @     0x7f562ea29748  paddle::framework::details::ExceptionHolder::Catch()
    @     0x7f562ea29748  paddle::framework::details::ExceptionHolder::Catch()
    @     0x7f562ead4b6e  paddle::framework::details::FastThreadedSSAGraphExecutor::RunOpSync()
    @     0x7f562ead4b6e  paddle::framework::details::FastThreadedSSAGraphExecutor::RunOpSync()
    @     0x7f562ead377f  paddle::framework::details::FastThreadedSSAGraphExecutor::RunOp()
    @     0x7f562ead3a44  _ZNSt17_Function_handlerIFvvESt17reference_wrapperISt12_Bind_simpleIFS1_ISt5_BindIFZN6paddle9framework7details28FastThreadedSSAGraphExecutor10RunOpAsyncEPSt13unordered_mapIPNS6_12OpHandleBaseESt6atomicIiESt4hashISA_ESt8equal_toISA_ESaISt4pairIKSA_SC_EEESA_RKSt10shared_ptrINS5_13BlockingQueueImEEEEUlvE_vEEEvEEEE9_M_invokeERKSt9_Any_data
    @     0x7f562ead377f  paddle::framework::details::FastThreadedSSAGraphExecutor::RunOp()
    @     0x7f562ead3a44  _ZNSt17_Function_handlerIFvvESt17reference_wrapperISt12_Bind_simpleIFS1_ISt5_BindIFZN6paddle9framework7details28FastThreadedSSAGraphExecutor10RunOpAsyncEPSt13unordered_mapIPNS6_12OpHandleBaseESt6atomicIiESt4hashISA_ESt8equal_toISA_ESaISt4pairIKSA_SC_EEESA_RKSt10shared_ptrINS5_13BlockingQueueImEEEEUlvE_vEEEvEEEE9_M_invokeERKSt9_Any_data
    @     0x7f562c5b8d43  std::_Function_handler<>::_M_invoke()
    @     0x7f562c5b8d43  std::_Function_handler<>::_M_invoke()
    @     0x7f562c348537  std::__future_base::_State_base::_M_do_set()
    @     0x7f5692ac6a99  __pthread_once_slow
    @     0x7f562c348537  std::__future_base::_State_base::_M_do_set()
    @     0x7f562eacef32  _ZNSt13__future_base11_Task_stateISt5_BindIFZN6paddle9framework7details28FastThreadedSSAGraphExecutor10RunOpAsyncEPSt13unordered_mapIPNS4_12OpHandleBaseESt6atomicIiESt4hashIS8_ESt8equal_toIS8_ESaISt4pairIKS8_SA_EEES8_RKSt10shared_ptrINS3_13BlockingQueueImEEEEUlvE_vEESaIiEFvvEE6_M_runEv
    @     0x7f5692ac6a99  __pthread_once_slow
    @     0x7f562eacef32  _ZNSt13__future_base11_Task_stateISt5_BindIFZN6paddle9framework7details28FastThreadedSSAGraphExecutor10RunOpAsyncEPSt13unordered_mapIPNS4_12OpHandleBaseESt6atomicIiESt4hashIS8_ESt8equal_toIS8_ESaISt4pairIKS8_SA_EEES8_RKSt10shared_ptrINS3_13BlockingQueueImEEEEUlvE_vEESaIiEFvvEE6_M_runEv
    @     0x7f562c34a764  _ZZN10ThreadPoolC1EmENKUlvE_clEv
    @     0x7f56534f6421  execute_native_thread_routine_compat
    @     0x7f562c34a764  _ZZN10ThreadPoolC1EmENKUlvE_clEv
    @     0x7f5692abf6ba  start_thread
    @     0x7f56534f6421  execute_native_thread_routine_compat
    @     0x7f56927f541d  clone
    @     0x7f5692abf6ba  start_thread
    @              (nil)  (unknown)
Aborted (core dumped)