Installation of Libmr, No module named numpy while building a container

I am trying to install a package Libmr inside my container. It says there is no module numpy, but I have added numpy in the requirement file. I guess Libmr needs Numpy to be installed prior to its installation.

Step #1: Collecting numpy==1.19.5
Step #1:   Downloading numpy-1.19.5-cp36-cp36m-manylinux2010_x86_64.whl (14.8 MB)
Step #1: Collecting libmr
Step #1:   Downloading (39 kB)
Step #1:     ERROR: Command errored out with exit status 1:
Step #1:      command: /env/bin/python -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-woar6lx9/libmr/'"'"'; __file__='"'"'/tmp/pip-install-woar6lx9/libmr/'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);'"'"'rn'"'"', '"'"'n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-pip-egg-info-a_kn5xwi
Step #1:          cwd: /tmp/pip-install-woar6lx9/libmr/
Step #1:     Complete output (5 lines):
Step #1:     Traceback (most recent call last):
Step #1:       File "<string>", line 1, in <module>
Step #1:       File "/tmp/pip-install-woar6lx9/libmr/", line 3, in <module>
Step #1:         import numpy
Step #1:     ModuleNotFoundError: No module named 'numpy'
Step #1:     ----------------------------------------
Step #1: ERROR: Command errored out with exit status 1: python egg_info Check the logs for full command output.
Step #1: WARNING: You are using pip version 20.2.2; however, version 21.0.1 is available.
Step #1: You should consider upgrading via the '/env/bin/python -m pip install --upgrade pip' command.
Step #1: The command '/bin/sh -c pip install -r requirements.txt' returned a non-zero code: 1
Finished Step #1
ERROR: build step 1 "[email protected]:fb864d4f2bc3b4642a77cfb96adab6c449b2592ba6d41db388c171134b12b275" failed: step exited with non-zero status: 1

Kindly suggest a fix

Source: Docker Questions