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Python3 (pip): find which package provides a particular module

Without getting confused, there are tons of questions about installing packages, how to import the resulting modules, and listing what packages are available. But there doesn't seem to be the equivalent of a "--what-provides" option for pip, if you don't have a requirements.txt or pipenv. This question is similar to a previous question, but asks for the parent package, and not additional metadata. That said, these other questions did not get a lot of attention or many accepted answers - eg. How do you find python package metadata information given a module. So forging ahead... .
By way of example, there are two packages (to name a few) that will install a module called "serial" - namely "pyserial" and "serial". So assuming that one of the packages was installed, we might find it by using pip list:
python3 -m pip list | grep serial
However, the problem comes in if the name of the package does not match the name of the module, or if you just want to find out what package to install, working on a legacy server or dev machine.
You can check the path of the imported module - which can give you a clue. But continuing the example...
>>> import serial
>>> print(serial.__file__)
/usr/lib/python3.6/site-packages/serial/__init__.py
It is in a "serial" directory, but only pyserial is in fact installed, not serial:
> python3 -m pip list | grep serial
pyserial 3.4
The closest I can come is to generate a requirements.txt via "pipreqs ./" which may fail on a dependent child file (as it does with me), or to reverse check dependencies via pipenv (which brings a whole set of new issues along to get it all setup):
> pipenv graph --reverse
cymysql==0.9.15
ftptool==0.7.1
netifaces==0.10.9
pip==20.2.2
PyQt5-sip==12.8.1
- PyQt5==5.15.0 [requires: PyQt5-sip>=12.8,<13]
setuptools==50.3.0
wheel==0.35.1
Does anyone know of a command that I have missed for a simple solution to finding what pip package provides a particular module?

Use the packages_distributions() function from importlib.metadata (or importlib-metadata). So for example, in your case where serial is the name of the "import package":
import importlib.metadata # or: `import importlib_metadata`
importlib.metadata.packages_distributions()['serial']
This should return a list containing pyserial, which is the name of the "distribution package" (the name that should be used to pip-install).
References
https://importlib-metadata.readthedocs.io/en/stable/using.html#package-distributions
https://github.com/python/importlib_metadata/pull/287/files
For older Python versions and/or older versions of importlib-metadata...
I believe something like the following should work:
#!/usr/bin/env python3
import importlib.util
import pathlib
import importlib_metadata
def get_distribution(file_name):
result = None
for distribution in importlib_metadata.distributions():
try:
relative = (
pathlib.Path(file_name)
.relative_to(distribution.locate_file(''))
)
except ValueError:
pass
else:
if distribution.files and relative in distribution.files:
result = distribution
break
return result
def alpha():
file_name = importlib.util.find_spec('serial').origin
distribution = get_distribution(file_name)
print("alpha", distribution.metadata['Name'])
def bravo():
import serial
file_name = serial.__file__
distribution = get_distribution(file_name)
print("bravo", distribution.metadata['Name'])
if __name__ == '__main__':
alpha()
bravo()
This is just an example of code showing how to get the metadata of the installed project a specific module belongs to.
The important bit is the get_distribution function, it takes a file name as an argument. It could be the file name of a module or package data. If that file name belongs to a project installed in the environment (via pip install for example) then the importlib.metadata.Distribution object is returned.

Edit 2023/01/31: This issue is now solved via the importlib_metadata library. See Provide mapping from "Python packages" to "distribution packages", specifically "Note 2" deals with this exact issue. As such, see comments by #sinoroc, you can locate the package (eg. package "pyserial" providing module "serial") with something like this:
>>> import importlib_metadata
>>> print(importlib_metadata.packages_distributions()['serial'])
['pyserial']
Building on #sinoroc's much-published answer, I came up with the following code (incorporating the mentioned importlib.util.find_spec method, but with a bash-based search against the RECORD file in the path returned). I also tried to implement #sinoroc's version - but was not successful. Both methods are included to demonstrate.
Run as "python3 python_find-module-package.py -m [module-name-here] -d", which will also print debug. Leave off the "-d" switch to get just the package name returned (and errors).
TLDR: Code on github.
#!/usr/bin/python3
import sys
import os.path
import importlib.util
import importlib_metadata
import pathlib
import subprocess
import argparse
parser = argparse.ArgumentParser()
parser.add_argument("-m", "--module", help="Find matching package for the specified Python module",
type=str)
#parser.add_argument("-u", "--username", help="Database username",
# type=str)
#parser.add_argument("-p", "--password", help="Database password",
# type=str)
parser.add_argument("-d", "--debug", help="Debug messages are enabled",
action="store_true")
args = parser.parse_args()
TESTMODULE='serial'
def debugPrint (message="Nothing"):
if args.debug:
print ("[DEBUG] %s" % str(message))
class application ():
def __init__(self, argsPassed):
self.argsPassed = argsPassed
debugPrint("Got these arguments:\n%s" % (argsPassed))
def run (self):
#debugPrint("Running with args:\n%s" % (self.argsPassed))
try:
if self.argsPassed.module is not None:
self.moduleName=self.argsPassed.module #i.e. the module that you're trying to match with a package.
else:
self.moduleName=TESTMODULE
print("[WARN] No module name supplied - defaulting to %s!" % (TESTMODULE))
self.location=importlib.util.find_spec(self.moduleName).origin
debugPrint(self.location)
except:
print("[ERROR] Parsing module name!")
exit(1)
try:
self.getPackage()
except Exception as e:
print ("[ERROR] getPackage failed: %s" % str(e))
try:
distResult=self.getDistribution(self.location)
self.packageStrDist=distResult.metadata['Name']
print(self.packageStrDist)
except Exception as e:
print ("[ERROR] getDistribution failed: %s" % str(e))
debugPrint("Parent package for \"%s\" is: \"%s\"" % (self.moduleName, self.packageStr))
return self.packageStr
def getPackage (self):
locationStr=self.location.split("site-packages/",1)[1]
debugPrint(locationStr)
#serial/__init__.py
locationDir=self.location.split(locationStr,1)[0]
debugPrint(locationDir)
#/usr/lib/python3.6/site-packages
cmd='find \"' + locationDir + '\" -type f -iname \'RECORD\' -printf \'\"%p\"\\n\' | xargs grep \"' + locationStr + '\" -l -Z'
debugPrint(cmd)
#find "/usr/lib/python3.6/site-packages" -type f -iname 'RECORD' -printf '"%p"\n' | xargs grep "serial/__init__.py" -l -Z
#return_code = os.system(cmd)
#return_code = subprocess.run([cmd], stdout=subprocess.PIPE, universal_newlines=True, shell=False)
#findResultAll = return_code.stdout
findResultAll = subprocess.check_output(cmd, shell=True) # Returns stdout as byte array, null terminated.
findResult = str(findResultAll.decode('ascii').strip().strip('\x00'))
debugPrint(findResult)
#/usr/lib/python3.6/site-packages/pyserial-3.4.dist-info/RECORD
findDir = os.path.split(findResult)
self.packageStr=findDir[0].replace(locationDir,"")
debugPrint(self.packageStr)
def getDistribution(self, fileName=TESTMODULE):
result = None
for distribution in importlib_metadata.distributions():
try:
relative = (pathlib.Path(fileName).relative_to(distribution.locate_file('')))
#except ValueError:
#except AttributeError:
except:
pass
else:
if relative in distribution.files:
result = distribution
return result
if __name__ == '__main__':
result=1
try:
prog = application(args)
result = prog.run()
except Exception as E:
print ("[ERROR] Prog Exception: %s" % str(E))
finally:
sys.exit(result)
# exit the program if we haven't already
print ("Shouldn't get here.")
sys.exit(result)

ImportError in python

In clean.py I have:
import datetime
import os
from flask_script import Manager
from sqlalchemy_utils import dependent_objects
from components import db, app
from modules.general.models import File
from modules.workflow import Workflow
manager = Manager(usage='Cleanup manager')
#manager.command
def run(dryrun=False):
for abandoned_workflow in Workflow.query.filter(Workflow.current_endpoint == "upload.upload_init"):
if abandoned_workflow.started + datetime.timedelta(hours=12) < datetime.datetime.utcnow():
print("Removing abandoned workflow {0} in project {1}".format(
abandoned_workflow.id, abandoned_workflow.project.name
))
if not dryrun:
db.session.delete(abandoned_workflow)
db.session.commit()
for file in File.query.all():
dependencies_number = dependent_objects(file).count()
print("File {0} at {1} has {2} dependencies".format(file.name, file.path, dependencies_number))
if not dependencies_number:
file_delete(file, dryrun)
if not dryrun:
db.session.delete(file)
db.session.commit()
# List all files in FILE_STORAGE directory and delete ones tat don't have records in DB
all_files_hash = list(zip(*db.session.query(File.hash).all()))
for file in os.listdir(app.config['FILE_STORAGE']):
if file.endswith('.dat'):
continue
if file not in all_files_hash:
file_delete(os.path.join(app.config['FILE_STORAGE'], file), dryrun)enter code here
I need start def run()
in console I write:
python clean.py
And I have outputs :
`Traceback (most recent call last):
File "cleanup_command.py", line 7, in <module>
from components import db, app
ImportError: No module named 'components'
clean.py is located in- C:\App\model\clean.py
components.py is located in - C:\components.py
Workflow.py is located in - C:\modules\workflow\Workflow.py
Please, tell me what could be the problem?

The problem is that modules for import are searched in certain locations: https://docs.python.org/2/tutorial/modules.html#the-module-search-path.
In your case you can put all source directory paths in PYTHONPATH var like:
PYTHONPATH=... python clean.py
But I guess it would be better to relocate your code files (i.e. put all the libs in one location)

To start run() when you call python clean.py, Add these lines at the end of the script.
if __name__ == '__main__':
r = run()
## 0-127 is a safe return range, and 1 is a standard default error
if r < 0 or r > 127: r = 1
sys.exit(r)
Also as Eugene Primako mentioned it is better to relocate your code files in one location.
from components import db, app
ImportError: No module named 'components'
This means its looking for script named components.py in a location where clean.py is placed. This is the reason why you have got import error.

python how to check if a module exists without importing it [duplicate]

How can I know if a Python module exists, without importing it?
Importing something that might not exist (not what I want) results in:
try:
import eggs
except ImportError:
pass

TL;DR) Use importlib.util.find_spec(module_name) (Python 3.4+).
Python2: imp.find_module
To check if import can find something in Python 2, using imp:
import imp
try:
imp.find_module('eggs')
found = True
except ImportError:
found = False
To find dotted imports, you need to do more:
import imp
try:
spam_info = imp.find_module('spam')
spam = imp.load_module('spam', *spam_info)
imp.find_module('eggs', spam.__path__) # __path__ is already a list
found = True
except ImportError:
found = False
You can also use pkgutil.find_loader (more or less the same as the Python 3 part:
import pkgutil
eggs_loader = pkgutil.find_loader('eggs')
found = eggs_loader is not None
Python 3
Python 3 ≤ 3.3: importlib.find_loader
You should use importlib. I went about doing this like:
import importlib
spam_loader = importlib.find_loader('spam')
found = spam_loader is not None
My expectation being, if you can find a loader for it, then it exists. You can also be a bit more smart about it, like filtering out what loaders you will accept. For example:
import importlib
spam_loader = importlib.find_loader('spam')
# only accept it as valid if there is a source file for the module - no bytecode only.
found = issubclass(type(spam_loader), importlib.machinery.SourceFileLoader)
Python 3 ≥ 3.4: importlib.util.find_spec
In Python 3.4 importlib.find_loader Python documentation was deprecated in favour of importlib.util.find_spec. The recommended method is the importlib.util.find_spec. There are others like importlib.machinery.FileFinder, which is useful if you're after a specific file to load. Figuring out how to use them is beyond the scope of this.
import importlib
spam_spec = importlib.util.find_spec("spam")
found = spam_spec is not None
This also works with relative imports, but you must supply the starting package, so you could also do:
import importlib
spam_spec = importlib.util.find_spec("..spam", package="eggs.bar")
found = spam_spec is not None
spam_spec.name == "eggs.spam"
While I'm sure there exists a reason for doing this - I'm not sure what it would be.
Warning
When trying to find a submodule, it will import the parent module (for ALL of the above methods)!
food/
|- __init__.py
|- eggs.py
## __init__.py
print("module food loaded")
## eggs.py
print("module eggs")
were you then to run
>>> import importlib
>>> spam_spec = importlib.util.find_spec("food.eggs")
module food loaded
ModuleSpec(name='food.eggs', loader=<_frozen_importlib.SourceFileLoader object at 0x10221df28>, origin='/home/user/food/eggs.py')
Comments are welcome on getting around this
Acknowledgements
#rvighne for importlib
#lucas-guido for Python 3.3+ deprecating find_loader
#enpenax for pkgutils.find_loader behaviour in Python 2.7

Python 3 >= 3.6: ModuleNotFoundError
The ModuleNotFoundError has been introduced in Python 3.6 and can be used for this purpose:
try:
import eggs
except ModuleNotFoundError:
# Error handling
pass
The error is raised when a module or one of its parents cannot be found. So
try:
import eggs.sub
except ModuleNotFoundError as err:
# Error handling
print(err)
would print a message that looks like No module named 'eggs' if the eggs module cannot be found; but it would print something like No module named 'eggs.sub' if only the sub module couldn't be found, but the eggs package could be found.
See the documentation of the import system for more information on the ModuleNotFoundError.

After using yarbelk's response, I've made this so I don't have to import ìmp.
try:
__import__('imp').find_module('eggs')
# Make things with a supposed existing module
except ImportError:
pass
It is useful in Django's settings.py file, for example.

Python 2, without relying on ImportError
Until the current answer is updated, here is the way for Python 2
import pkgutil
import importlib
if pkgutil.find_loader(mod) is not None:
return importlib.import_module(mod)
return None
Why another answer?
A lot of answers make use of catching an ImportError. The problem with that is, that we cannot know what throws the ImportError.
If you import your existent module and there happens to be an ImportError in your module (e.g., typo on line 1), the result will be that your module does not exist.
It will take you quite the amount of backtracking to figure out that your module exists and the ImportError is caught and makes things fail silently.

go_as's answer as a one-liner:
python -c "help('modules');" | grep module

Use one of the functions from pkgutil, for example:
from pkgutil import iter_modules
def module_exists(module_name):
return module_name in (name for loader, name, ispkg in iter_modules())

I wrote this helper function:
def is_module_available(module_name):
if sys.version_info < (3, 0):
# python 2
import importlib
torch_loader = importlib.find_loader(module_name)
elif sys.version_info <= (3, 3):
# python 3.0 to 3.3
import pkgutil
torch_loader = pkgutil.find_loader(module_name)
elif sys.version_info >= (3, 4):
# python 3.4 and above
import importlib
torch_loader = importlib.util.find_spec(module_name)
return torch_loader is not None

Here is a way to check if a module is loaded from the command line:
Linux/UNIX script file method: make a file module_help.py:
#!/usr/bin/env python
help('modules')
Then make sure it's executable: chmod u+x module_help.py
And call it with a pipe to grep:
./module_help.py | grep module_name
Invoke the built-in help system. (This function is intended for interactive use.) If no argument is given, the interactive help system starts on the interpreter console. If the argument is a string, then the string is looked up as the name of a module, function, class, method, keyword, or documentation topic, and a help page is printed on the console. If the argument is any other kind of object, a help page on the object is generated.
Interactive method: in the console, load python
>>> help('module_name')
If found, quit reading by typing q.
To exit the Python interpreter interactive session, press Ctrl + D
Windows script file method, also Linux/UNIX compatible, and better overall:
#!/usr/bin/env python
import sys
help(sys.argv[1])
Calling it from the command like:
python module_help.py site
Would output:
Help on module site:
NAME
site - Append module search paths for third-party packages to sys.path.
FILE
/usr/lib/python2.7/site.py
MODULE DOCS
http://docs.python.org/library/site
DESCRIPTION
...
:
And you'd have to press q to exit interactive mode.
Using it for an unknown module, e.g.,
python module_help.py lkajshdflkahsodf
Would output:
no Python documentation found for 'lkajshdflkahsodf'
and exit.

You could just write a little script that would try to import all the modules and tell you which ones are failing and which ones are working:
import pip
if __name__ == '__main__':
for package in pip.get_installed_distributions():
pack_string = str(package).split(" ")[0]
try:
if __import__(pack_string.lower()):
print(pack_string + " loaded successfully")
except Exception as e:
print(pack_string + " failed with error code: {}".format(e))
Output:
zope.interface loaded successfully
zope.deprecation loaded successfully
yarg loaded successfully
xlrd loaded successfully
WMI loaded successfully
Werkzeug loaded successfully
WebOb loaded successfully
virtualenv loaded successfully
...
A word of warning: this will try to import everything, so you'll see things like PyYAML failed with error code: No module named pyyaml, because the actual import name is just yaml. So as long as you know your imports, this should do the trick for you.

There isn't any way to reliably check if "dotted module" is importable without importing its parent package. Saying this, there are many solutions to problem "how to check if a Python module exists".
The below solution addresses the problem that an imported module can raise an ImportError even if it exists. We want to distinguish that situation from such in which the module does not exist.
Python 2:
import importlib
import pkgutil
import sys
def find_module(full_module_name):
"""
Returns module object if module `full_module_name` can be imported.
Returns None if module does not exist.
Exception is raised if (existing) module raises exception during its import.
"""
module = sys.modules.get(full_module_name)
if module is None:
module_path_tail = full_module_name.split('.')
module_path_head = []
loader = True
while module_path_tail and loader:
module_path_head.append(module_path_tail.pop(0))
module_name = ".".join(module_path_head)
loader = bool(pkgutil.find_loader(module_name))
if not loader:
# Double check if module realy does not exist
# (case: full_module_name == 'paste.deploy')
try:
importlib.import_module(module_name)
except ImportError:
pass
else:
loader = True
if loader:
module = importlib.import_module(full_module_name)
return module
Python 3:
import importlib
def find_module(full_module_name):
"""
Returns module object if module `full_module_name` can be imported.
Returns None if module does not exist.
Exception is raised if (existing) module raises exception during its import.
"""
try:
return importlib.import_module(full_module_name)
except ImportError as exc:
if not (full_module_name + '.').startswith(exc.name + '.'):
raise

In django.utils.module_loading.module_has_submodule:
import sys
import os
import imp
def module_has_submodule(package, module_name):
"""
check module in package
django.utils.module_loading.module_has_submodule
"""
name = ".".join([package.__name__, module_name])
try:
# None indicates a cached miss; see mark_miss() in Python/import.c.
return sys.modules[name] is not None
except KeyError:
pass
try:
package_path = package.__path__ # No __path__, then not a package.
except AttributeError:
# Since the remainder of this function assumes that we're dealing with
# a package (module with a __path__), so if it's not, then bail here.
return False
for finder in sys.meta_path:
if finder.find_module(name, package_path):
return True
for entry in package_path:
try:
# Try the cached finder.
finder = sys.path_importer_cache[entry]
if finder is None:
# Implicit import machinery should be used.
try:
file_, _, _ = imp.find_module(module_name, [entry])
if file_:
file_.close()
return True
except ImportError:
continue
# Else see if the finder knows of a loader.
elif finder.find_module(name):
return True
else:
continue
except KeyError:
# No cached finder, so try and make one.
for hook in sys.path_hooks:
try:
finder = hook(entry)
# XXX Could cache in sys.path_importer_cache
if finder.find_module(name):
return True
else:
# Once a finder is found, stop the search.
break
except ImportError:
# Continue the search for a finder.
continue
else:
# No finder found.
# Try the implicit import machinery if searching a directory.
if os.path.isdir(entry):
try:
file_, _, _ = imp.find_module(module_name, [entry])
if file_:
file_.close()
return True
except ImportError:
pass
# XXX Could insert None or NullImporter
else:
# Exhausted the search, so the module cannot be found.
return False

In case you know the location of file and want to check that the respective Python code file has that module or not, you can simply check via the astor package in Python. Here is a quick example:
"""
Check if a module function exists or not without importing a Python package file
"""
import ast
import astor
tree = astor.parse_file('handler.py')
method_to_check = 'handle'
for item in tree.body:
if isinstance(item, ast.FunctionDef):
if item.name == method_to_check:
print('method exists')
break

A simpler if statement from Ask Ubuntu, How do I check whether a module is installed in Python?:
import sys
print('eggs' in sys.modules)

You can also use importlib.util directly
import importlib.util
def module_exists_without_import(module_name):
spec = importlib.util.find_spec(module_name)
return spec is not None

NameError while handling command line arguments

I was trying out a few python test scripts with sqlite3.
Here is the script that I wrote
#!/usr/bin/env python
from sqlite3 import dbapi2 as sqlite
from sys import argv,exit
db_name = "filenames.db"
def define_db():
try:
conn = sqlite.connect(db_name)
except IOError as e:
print "problem while creating/connecting the db:",e.args[0]
exit(1)
return conn
def write_db(conn,cursor,fni):
conn.execute("CREATE TABLE IF NOT EXISTS file (filenames TEXT UNIQUE)")
query = "INSERT OR REPLACE INTO file VALUES($filenames)"
cursor.execute(query,[fni])
cursor.close()
conn.commit()
conn.close()
print fni,"should now be in the db"
exit(0)
if __name__ == "__main__":
if len(argv) == 2:
etag = argv[1]
else:
print "no argument given - stopping now"
exit(1)
conn = define_db()
cursor = conn.cursor()
write_db(conn,cursor,fni)
I keep getting this error and was not able to solve it.
Traceback (most recent call last):
File "blah.py", line 37, in <module>
write_db(conn,cursor,fni)
NameError: name 'fni' is not defined
Any idea what the problem is.
At this moment I use python 2.7.3

The last line of your script refers to a name fni that is not defined.

You have not defined the variable "fni", but you are using it.

Static analysis tools like pyflakes or pylint can be useful to catch silly errors like this
If you wrote the bulk of the code in a function (so it doesn't assume blub is a global variable, which don't make pyflakes/pylint complain):
def main():
if len(argv) == 2:
blub = argv[1]
else:
print "no argument given - stopping now"
exit(1)
conn = define_db()
cursor = conn.cursor()
write_db(conn,cursor,fni)
if __name__ == "__main__":
main()
...then you would get a pair of errors, which points out exactly what the error is (you stored the argument in blub, but tried to access it with fni):
$ pip install pyflakes
$ pyflakes example.py
example.py:30: local variable 'blub' is assigned to but never used
example.py:37: undefined name 'fni'

Checking for module availability programmatically in Python?

given a list of module names (e.g. mymods = ['numpy', 'scipy', ...]) how can I check if the modules are available?
I tried the following but it's incorrect:
for module_name in mymods:
try:
import module_name
except ImportError:
print "Module %s not found." %(module_name)
thanks.

You could use both the __import__ function, as in #Vinay's answer, and a try/except, as in your code:
for module_name in mymods:
try:
__import__(module_name)
except ImportError:
print "Module %s not found." %(module_name)
Alternatively, to just check availability but without actually loading the module, you can use standard library module imp:
import imp
for module_name in mymods:
try:
imp.find_module(module_name)
except ImportError:
print "Module %s not found." %(module_name)
this can be substantially faster if you do only want to check for availability, not (yet) load the modules, especially for modules that take a while to load. Note, however, that this second approach only specifically checks that the modules are there -- it doesn't check for the availability of any further modules that might be required (because the modules being checked try to import other modules when they load). Depending on your exact specs, this might be a plus or a minus!-)

Use the __import__ function:
>>> for mname in ('sys', 'os', 're'): __import__(mname)
...
<module 'sys' (built-in)>
<module 'os' from 'C:\Python\lib\os.pyc'>
<module 're' from 'C:\Python\lib\re.pyc'>
>>>

Nowadays, more than 10 years after the question, in Python >= 3.4, the way to go is using importlib.util.find_spec:
import importlib
spec = importlib.util.find_spec('path.to.module')
if spam:
print('module can be imported')
This mechanism is them preferred over imp.find_module:
import importlib.util
import sys
# this is optional set that if you what load from specific directory
moduledir="d:\\dirtest"
```python
try:
spec = importlib.util.find_spec('path.to.module', moduledir)
if spec is None:
print("Import error 0: " + " module not found")
sys.exit(0)
toolbox = spec.loader.load_module()
except (ValueError, ImportError) as msg:
print("Import error 3: "+str(msg))
sys.exit(0)
print("load module")
For old Python versions also look how to check if a python module exists without importing it