Numpy array interface does not promote bool/int types when multiplied by scalar float

[aarmey]

Description

Multiplying a bool/int-typed array with a scalar float promotes the output type to a float in Numpy. I believe this also happens using the older MXNet interface. However, MXNet.numpy arrays retain their old type.

Error Message

There is no error message, just inconsistent behavior compared to Numpy.

To Reproduce

import mxnet as mx
from mxnet import numpy as np

A = np.array([0, 1, 0], dtype=np.bool)
B = np.array([0, 1, 2], dtype=np.int64)
C = np.array([0, 1, 2], dtype=np.float64)

print(A * 3.9)
print(B * 3.9)
print(C * 3.9)

Outputs:

[0 3 0]
[0 3 6]
[0.  3.9 7.8]

Environment

Environment Information

----------Python Info----------
Version : 3.8.6
Compiler : GCC 9.3.0
Build : ('default', 'Oct 26 2020 14:01:59')
Arch : ('64bit', 'ELF')
------------Pip Info-----------
Version : 21.0.1
Directory : /usr/local/lib/python3.8/site-packages/pip
----------MXNet Info-----------
Version : 1.7.0
Directory : /usr/local/lib/python3.8/site-packages/mxnet
Commit Hash : 64f737c
64f737c
64f737c
64f737c
64f737c
64f737c
64f737c
64f737c
64f737c
64f737c
Library : ['/usr/local/lib/python3.8/site-packages/mxnet/libmxnet.so']
Build features:
✖ CUDA
✖ CUDNN
✖ NCCL
✖ CUDA_RTC
✖ TENSORRT
✔ CPU_SSE
✔ CPU_SSE2
✔ CPU_SSE3
✔ CPU_SSE4_1
✔ CPU_SSE4_2
✖ CPU_SSE4A
✔ CPU_AVX
✖ CPU_AVX2
✔ OPENMP
✖ SSE
✔ F16C
✖ JEMALLOC
✔ BLAS_OPEN
✖ BLAS_ATLAS
✖ BLAS_MKL
✖ BLAS_APPLE
✔ LAPACK
✔ MKLDNN
✔ OPENCV
✖ CAFFE
✖ PROFILER
✔ DIST_KVSTORE
✖ CXX14
✖ INT64_TENSOR_SIZE
✔ SIGNAL_HANDLER
✖ DEBUG
✖ TVM_OP
----------System Info----------
Platform : Linux-5.8.0-41-generic-x86_64-with-glibc2.2.5
system : Linux
node : aretha
release : 5.8.0-41-generic
version : #46-Ubuntu SMP Mon Jan 18 16:48:44 UTC 2021
----------Hardware Info----------
machine : x86_64
processor : x86_64
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
Address sizes: 43 bits physical, 48 bits virtual
CPU(s): 32
On-line CPU(s) list: 0-31
Thread(s) per core: 2
Core(s) per socket: 16
Socket(s): 1
NUMA node(s): 2
Vendor ID: AuthenticAMD
CPU family: 23
Model: 1
Model name: AMD Ryzen Threadripper 1950X 16-Core Processor
Stepping: 1
Frequency boost: enabled
CPU MHz: 2561.528
CPU max MHz: 3400.0000
CPU min MHz: 2200.0000
BogoMIPS: 6786.49
Virtualization: AMD-V
L1d cache: 512 KiB
L1i cache: 1 MiB
L2 cache: 8 MiB
L3 cache: 32 MiB
NUMA node0 CPU(s): 0-7,16-23
NUMA node1 CPU(s): 8-15,24-31
Vulnerability Itlb multihit: Not affected
Vulnerability L1tf: Not affected
Vulnerability Mds: Not affected
Vulnerability Meltdown: Not affected
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl and seccomp
Vulnerability Spectre v1: Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2: Mitigation; Full AMD retpoline, STIBP disabled, RSB filling
Vulnerability Srbds: Not affected
Vulnerability Tsx async abort: Not affected
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt
pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid amd_dcm aperfmperf pni pclmulqdq monitor ssse3 fma
cx16 sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnow
prefetch osvw skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_llc mwaitx cpb hw_pstate sme ssbd sev vmmcall fsgsba
se bmi1 avx2 smep bmi2 rdseed adx smap clflushopt sha_ni xsaveopt xsavec xgetbv1 xsaves clzero irperf xsaveerptr arat npt lbrv
svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold avic v_vmsave_vmload vgif overflow_re
cov succor smca
----------Network Test----------
Setting timeout: 10
Timing for MXNet: https://github.com/apache/incubator-mxnet, DNS: 0.0054 sec, LOAD: 0.4757 sec.
Timing for Gluon Tutorial(en): http://gluon.mxnet.io, DNS: 0.2448 sec, LOAD: 0.2354 sec.
Error open Gluon Tutorial(cn): https://zh.gluon.ai, <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: certificate has expired (_ssl.c:1124)>, DNS finished in 0.970501184463501 sec.
Timing for FashionMNIST: https://apache-mxnet.s3-accelerate.dualstack.amazonaws.com/gluon/dataset/fashion-mnist/train-labels-idx1-ubyte.gz, DNS: 0.0352 sec, LOAD: 0.0971 sec.
Timing for PYPI: https://pypi.python.org/pypi/pip, DNS: 0.0439 sec, LOAD: 0.3022 sec.
Error open Conda: https://repo.continuum.io/pkgs/free/, HTTP Error 403: Forbidden, DNS finished in 0.16263580322265625 sec.
----------Environment----------
KMP_DUPLICATE_LIB_OK="True"
KMP_INIT_AT_FORK="FALSE"

[github-actions]

Welcome to Apache MXNet (incubating)! We are on a mission to democratize AI, and we are glad that you are contributing to it by opening this issue.
Please make sure to include all the relevant context, and one of the @apache/mxnet-committers will be here shortly.
If you are interested in contributing to our project, let us know! Also, be sure to check out our guide on contributing to MXNet and our development guides wiki.

[leezu]

Hi Aaron, the Numpy interface in v1.x is experimental and contains some issues. I confirmed the bug isn't present in MXNet 2. I think you currently have some workarounds for this bug on v1.x. I recommend you keep them for now and the issue will be resolved once v2 is stable

[aarmey]

Great, thanks @leezu.