We will introduce frequently used commands to complicated commands for each usage case.

Case 1. Dependency care

The script doesn't work because of a problem with the package dependencies ...

(1) Check for dependency issues.

$ pip check
#If there are no problems with the package dependencies,
# No broken requirements found.
#Is output.

(2) After confirming the requested version of the package, check the available version.

$ pip install <package>==
# ERROR: Could not find a version that satisfies the requirement <package>== (...
#Error is output, and you can check the available package version.

(3) Install by specifying the version

$ pip install <package>==<version>

#When you want to be up to date
$ pip install -U <package>
#When you want to update to the latest version below a certain version
$ pip install -U "<package> < <version>" #Inequality sign<I'm using.

Check installed package dependencies

Use show to see the dependencies along with the package details.

$ pip show <package>

You can use the pipdeptree package to display dependencies that include version information.

$ pip install pipdeptree

# <package>Shows the package requested by and its version.
$ pipdeptree -p <packgage>
# <package>View the package that requests and the version that is requested.
$ pipdeptree -r -p <packgage>

Check details & dependencies of packages not installed

You can also find out more about uninstalled packages by asking PyPi as follows:

import request
from pprint import pprint #Import for output formatting

package = '<package>'
version = '<version>'
url = f'https://pypi.org/pypi/{package}/{version}/json'
#If you do not specify the version
# url = f'https://pypi.org/pypi/{package}/json'

json = requests.get(url).json()
pprint(json['info'])

You can check the packages required by the specified package as follows.

pprint(json['info']['requires_dist'])

Case 2. Install the package in an offline environment

I want to pip install <package> at the destination connected with ssh, but the connection destination is offline!

(1) First, download the required package online directly under ./src (if you want to specify the version, use<package> == <version>).

$ pip download -d ./src <package>
# or
$ pip download -d ./src -r requirements.txt

(2) Transfer ./src with scp.

$ scp -r -C ./src <user>@<host>:<path>

#If the capacity is large, compress it and send it.
$ tar czf src.tar.gz src
$ scp -C ./src.tar.gz <user>@<host>:<path>

(3) After connecting with ssh, enter the src directory. Installation is complete with the following command!

$ pip install <package (file name)> #Install one by one from the current directory.
# or 
$ pip install ./* #Install all at once.

#If you compressed src, decompress it in advance.
$ tar xzf src.tar.gz

This and that of `pip download`

Download the source package.

$ pip download -d ./src --no-binary :all: <package>

Download the binary package by specifying the version and platform.

$ pip download -d ./src --only-binary :all: --platform <platform> --python-version <python_version> --implementation <implementation> --abi <abi> <package>

Below is a reference page.

Case 3. Change the save destination of `pip install`

I want to try a certain package, but I don't want to pollute the global and local pips. Not enough to use a virtual environment ...

(1) Specify the directory and install the package.

$ pip install -t <dir> <package>

(2) By adding the following line to the script, the package directly under <dir> can be used.

import sys
sys.path.append(dirpath)

#How to specify the path Part 1
import os
dirpath = sys.path.append(os.path.join(os.path.dirname(__file__), '<dir>Relative path'))
#How to specify the path Part 2
from pathlib import Path
dirpath = sys.path.append(str((Path(__file__).parent/'<dir>Relative path').resolve()))
#How to specify the path Part 3
dirpath = '<dir>Absolute path'

You can also execute it by writing a relative path in dirpath, but if you want to call the written script from another script, you need to use __file__ or specify dirpath as an absolute path.

(3) Delete the directory when you no longer need the package.

$ rm -r <dir>

I want to try a different version of an installed package

If you run the script in the directory <dir> where you installed the packages, the packages in <dir> will be preferentially imported.

If you run the script outside of <dir> and want to use another version of the package that is already installed globally or locally, add the following line.

sys.path = sys.path[::-1]

The package is read preferentially from the first path of sys.path. By reversing the list after adding a new path, the added path can be read with the highest priority.

Don't you know it? pip command