There is a great tool to get pip package dependencies called pipdeptree.

To see the output of my whole requirements file I did this script:

cat requirements.txt | cut -d "=" -f 1 | cut -d "[" -f 1 | xargs -I{} pipdeptree -p {}

Here is an example result

celery==4.2.0
  - billiard [required: >=3.5.0.2,<3.6.0, installed: 3.5.0.3]
  - kombu [required: >=4.2.0,<5.0, installed: 4.2.1]
    - amqp [required: >=2.1.4,<3.0, installed: 2.3.2]
      - vine [required: >=1.1.3, installed: 1.1.4]
  - pytz [required: >dev, installed: 2018.5]
environs==2.1.1
  - marshmallow [required: >=2.7.0, installed: 2.15.3]
  - read-env [required: >=1.1.0, installed: 1.1.0]
future==0.16.0