Python script to check if specified package(s) are installed. Scan the requirements.txt instead, if no package specified.

checkpkg.py

##
# Check if specified package(s) are installed.
# Displays a GUI message if any aren't and asks to install.

import sys, os
import subprocess
import re
import importlib.util
import tkinter as tk
import tkinter.messagebox as messagebox

def install_packages(*packages):
    for pkg in packages:
        subprocess.check_call([sys.executable, '-m', 'pip', 'install', pkg])

def check(*packages):
    ##modules = ['csv', 'PIL', 'foob']
    if len(packages) == 0:
        if not os.path.exists('requirements.txt'): return
        packages = []
        pattern = "([a-zA-Z0-9_]*)([\s]*)([>|=|<]{0,2})([\s]*)(.*)"
        for line in open('requirements.txt','r').read().splitlines():
            #print(pattern, line)
            m = re.match(pattern, line)
            #print("adding package %s from requirements.txt" % m[1])
            pkg = m[1]
            if pkg.strip() == "": continue
            packages.append( pkg)

    not_found = []
    for pkg in packages:
        print("checking package %s" % pkg)
        try:
            subprocess.check_output('py -m pip show ' + pkg, stderr=subprocess.STDOUT)
        except subprocess.CalledProcessError as ex:
            not_found.append(pkg)
            print('missing...')
        # if pkg in sys.modules:
            # pass
        # elif importlib.util.find_spec(pkg) is not None:
            # pass
        # else:
            # not_found.append(pkg)
    print("%d packages to be installed" % len(not_found))
    root = tk.Tk()
    #root.overrideredirect(1)
    root.withdraw()
    if len(not_found) > 0:
        ss = ",".join(not_found)
        r = messagebox.askyesno("", "Package(s) not found:\n\n" + ss + "\n\nDo you want to install them?")
        #print("R:", r)
        if r: 
            install_packages(*not_found)
            messagebox.showinfo("", "Package(s) installed successfully.")
        root.destroy()
        #return True
    else:
        messagebox.showinfo("", "All OK.")
        
def main():
    check()

if __name__ == "__main__":
    main()