This should do the trick at least for demo purposes. Simply call isLatestVersion with the name of the package you would like to check. If you are using this somewhere important you would want to try/catch the url request as internet access may not be available. Also note that if the package is not installed isLatestVersion will return False.

This is tested for Python 3.7.4 and Pip 19.0.3.

import pip
import subprocess
import json
import urllib.request
from pip._internal.operations.freeze import freeze

def isLatestVersion(pkgName):
    # Get the currently installed version
    current_version = ''
    for requirement in freeze(local_only=False):
        pkg = requirement.split('==')
        if pkg[0] == pkgName:
            current_version = pkg[1]

    # Check pypi for the latest version number
    contents = urllib.request.urlopen('https://pypi.org/pypi/'+pkgName+'/json').read()
    data = json.loads(contents)
    latest_version = data['info']['version']

    return latest_version == current_version

My project johnnydep has this feature.

In shell:

pip install --upgrade pip johnnydep
pip install gekko==0.2.0

In Python:

>>> from johnnydep.lib import JohnnyDist
>>> dist = JohnnyDist("gekko")
>>> dist.version_installed  
'0.2.0'
>>> dist.version_latest 
'0.2.3'

Edit: Remove pip search

Thanks for the several suggestions. Here is a new version that doesn’t use pip search but instead pulls the latest version directly from pypi as proposed by Daniel Hill. This also resolves the issue with the substring false matches.

def check(name):
    import subprocess
    import sys
    import json
    import urllib.request

    # create dictionary of package versions
    pkgs = subprocess.check_output([sys.executable, '-m', 'pip', 'freeze'])
    keys = [p.decode().split('==')[0] for p in pkgs.split()]
    values = [p.decode().split('==')[1] for p in pkgs.split()]
    d = dict(zip(keys, values)) # dictionary of all package versions

    # retrieve info on latest version
    contents = urllib.request.urlopen('https://pypi.org/pypi/'+name+'/json').read()
    data = json.loads(contents)
    latest_version = data['info']['version']

    if d[name]==latest_version:
        print('Latest version (' + d[name] + ') of '+str(name)+' is installed')
        return True
    else:
        print('Version ' + d[name] + ' of '+str(name)+' not the latest '+latest_version)
        return False

print(check('gekko'))

Original Response

Here is a fast solution that retrieves latest version information on only the gekko package of interest.

def check(name):
    import subprocess
    import sys
    # create dictionary of package versions
    pkgs = subprocess.check_output([sys.executable, '-m', 'pip', 'freeze'])
    keys = [p.decode().split('==')[0] for p in pkgs.split()]
    values = [p.decode().split('==')[1] for p in pkgs.split()]
    d = dict(zip(keys, values)) # dictionary of all package versions

    # retrieve info on latest version
    s = subprocess.check_output([sys.executable, '-m', 'pip', 'search', name])

    if d[name] in s.decode():  # weakness
        print('Latest version (' + d[name] + ') of '+str(name)+' is installed')
        return True
    else:
        print(s.decode())
        return False

print(check('gekko'))

This produces the message Latest version (0.2.3) of gekko is installed and returns True to indicate latest version (or False if not the latest version). This may not be the best solution because it only checks for a version substring with if d[name] in s.decode(): but it is faster than pip list --outdated that checks all the packages. This isn’t the most reliable method because it will return an incorrect True if current installed version is 0.2.3 but latest version is 0.2.30 or 0.2.3a. An improvement would be to programmatically get the latest version and do a direct comparison.

It’s not hard to write a simple script yourself by querying the PyPI API. With the latest Python 3.8, it’s possible using only the standard library (when using Python 3.7 or older, you’ll have to install the importlib_metadata backport):

# check_version.py

import json
import urllib.request
import sys

try:
    from importlib.metadata import version
except ImportError:
    from importlib_metadata import version

from distutils.version import LooseVersion


if __name__ == '__main__':
    name = sys.argv[1]
    installed_version = LooseVersion(version(name))

    # fetch package metadata from PyPI
    pypi_url = f'https://pypi.org/pypi/{name}/json'
    response = urllib.request.urlopen(pypi_url).read().decode()
    latest_version = max(LooseVersion(s) for s in json.loads(response)['releases'].keys())

    print('package:', name, 'installed:', installed_version, 'latest:', latest_version)

Usage example:

$ python check_version.py setuptools
package: setuptools installed: 41.2.0 latest: 41.6.0

If you’re happen to have packaging installed, it’s a better alternative to distutils.version for version parsing:

from distutils.version import LooseVersion

...

LooseVersion(s)

becomes

from packaging.version import parse

...

parse(s)

Checking Installed version:

One way to check installed version is just to access the __version__ attribute of the top-level namespace:

>>> import gekko
>>> gekko.__version__
'0.2.0'

Unfortunately not all projects set this attribute, it’s just a common convention in Python. When they don’t have a version attribute, you can use importlib.metadata to query the package version. This way does not actually require importing the package itself, since it’s retrieved from the package metadata which gets written out when the package was installed.

>>> import importlib.metadata
>>> importlib.metadata.version("gekko")
'0.2.0'

This functionality is available since Python 3.8. In older Python versions, you can use pkg_resources similarly, which is a part of setuptools:

>>> import pkg_resources
>>> pkg_resources.get_distribution("gekko").version
'0.2.0'

Checking Latest version:

There isn’t currently a way to do this within stdlib. But my project luddite has this feature:

>>> import luddite
>>> luddite.get_version_pypi("gekko")
'0.2.3'

To just check the latest version on PyPi (for Python 3.6 and up):

pip install requests

Then:

import requests

package = 'django'  # replace with the package you want to check
response = requests.get(f'https://pypi.org/pypi/{package}/json')
latest_version = response.json()['info']['version']

Based on the accepted answer you can do:

pip list --outdated | grep name_of_package

For pydicom these work fine,

import pydicom
print(pydicom.__version__) # output is a string: 'x.y.z'

or

import pydicom
print(pydicom.__version_info__) # output is a tuple: ('x', 'y', 'z')