Modules and Packages

Modules are files that contain functions, variables or classes that can be used without redefining them. They’re generally written in Python.

Packages are directory or folders which conatin a number of modules or packages in them.

Few built-in Modules are: 1. __builtins__ 0. __file__ 2. math 3. cmath 2. sys 4. os 5. itertools 6. string

The basics of working with module are discussed using a file prime_generator.py

Code:

from time import *
from itertools import *
from math import *

def prime_gen(n):
    num = 2
    while num <= n:
        k = 2
        while k * k <= num:
            if num % k == 0:
                break
            k += 1
        else:
            yield num
    num += 1

prime = 2
prime_square = 4
__primeval = 3

if __name__ == '__main__':
    t = time()
    for i in prime_gen(10 ** 2):
        print(i)
    print(time()-t)

Contents: 1. prime_gen - function or generator 2. prime - varaiable (constant when imported) 3. prime_square - variable (constant when imported) 4. __primeval - private value

import statement:

The import keyword is used to import a module or package.

Syntax:

import module_name

IN [1]

import prime_generator

for i in prime_generator.prime_gen(20):
    print(i, end=' ')

stdout

2 3 5 7 11 13 17 19

from statement:

The from keyword is used to import a specific set of functions or classes from a module.

Syntax:

from module_name import function_name

IN [2]

from prime_generator import prime_gen

for i in prime_gen(20):
    print(i, end=' ')

stdout

2 3 5 7 11 13 17 19

Importing all the objects from the module:

To import all the functions or objects, use * .

Syntax:

from module_name import *

IN [3]

from prime_generator import *

for i in prime_gen(20):
    print(i, end=' ')

stdout

2 3 5 7 11 13 17 19

as Keyword:

as Keyword is used to have a custom name for imported module or function.

Syntax:

import moule_name as custom_name
from module_name import function_name as custom_name

IN [4]

import prime_generator as pg

for i in pg.prime_gen(20):
    print(i, end=' ')

stdout

2 3 5 7 11 13 17 19

IN [6]

from prime_generator import prime_gen as pgf

for i in pgf(20):
    print(i, end=' ')

stdout

2 3 5 7 11 13 17 19

name:

It returns the name of the module without the extension. If called for main executing program (main module), it returns ‘__main__‘

Syntax:

module_name.__name__

IN [8]

import prime_generator as pg

print(pg.__name__)
print(__name__)

stdout

prime_generator
__main__

dir method:

Returns the list of attributes (that are relevant) of an object or a module. By default, it gives the details of main module.

Syntax:

dir([object])

IN [1]

import prime_generator

print(dir(prime_generator))
print()
print(dir(prime_generator.prime_gen))
print()
print(dir())

stdout

['__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__primeval', '__spec__', 'accumulate', 'acos', 'acosh', 'altzone', 'asctime', 'asin', 'asinh', 'atan', 'atan2', 'atanh', 'ceil', 'chain', 'comb', 'combinations', 'combinations_with_replacement', 'compress', 'copysign', 'cos', 'cosh', 'count', 'ctime', 'cycle', 'daylight', 'degrees', 'dist', 'dropwhile', 'e', 'erf', 'erfc', 'exp', 'expm1', 'fabs', 'factorial', 'filterfalse', 'floor', 'fmod', 'frexp', 'fsum', 'gamma', 'gcd', 'get_clock_info', 'gmtime', 'groupby', 'hypot', 'inf', 'isclose', 'isfinite', 'isinf', 'islice', 'isnan', 'isqrt', 'lcm', 'ldexp', 'lgamma', 'localtime', 'log', 'log10', 'log1p', 'log2', 'mktime', 'modf', 'monotonic', 'monotonic_ns', 'nan', 'nextafter', 'perf_counter', 'perf_counter_ns', 'perm', 'permutations', 'pi', 'pow', 'prime', 'prime_gen', 'prime_square', 'process_time', 'process_time_ns', 'prod', 'product', 'radians', 'remainder', 'repeat', 'sin', 'sinh', 'sleep', 'sqrt', 'starmap', 'strftime', 'strptime', 'struct_time', 'takewhile', 'tan', 'tanh', 'tau', 'tee', 'thread_time', 'thread_time_ns', 'time', 'time_ns', 'timezone', 'trunc', 'tzname', 'ulp', 'zip_longest']

['__annotations__', '__call__', '__class__', '__closure__', '__code__', '__defaults__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__get__', '__getattribute__', '__globals__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__kwdefaults__', '__le__', '__lt__', '__module__', '__name__', '__ne__', '__new__', '__qualname__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__']

['In', 'Out', '_', '__', '___', '__builtin__', '__builtins__', '__doc__', '__loader__', '__name__', '__package__', '__spec__', '_dh', '_i', '_i1', '_ih', '_ii', '_iii', '_oh', 'exit', 'get_ipython', 'prime_generator', 'quit']

namespace:

A container that has a list of names (objects) defined in a module. It is the place where python searches for objects defined and used in a function.

Global, Local and Built-in Namespaces

Global:

Namespace containing values defined throughout a file or module (globally)

Local:

Namespace containing values defined in a part of a file or module (Locally)

Builtin:

Namespace containing values common for all python file.

Order of Search:

Local
Global
Builtin

Packages:

Directory or folder containing a number of modules and subpackages.

It contains ‘__init__.py’ file which defines the modules that can be imported from the package.

Importing a module from package:

import package_name.module_name
import package_name.module_name as custom_name

Import a specific object from a module:

from package_name.module_name import object_name

Builtins:

__builtins__ module contains the list of methods and variables that are standard definitions in Python.

IN [8]

builtin = dir(__builtins__)
for i in builtin:
    print(i)

stdout

ArithmeticError
AssertionError
AttributeError
BaseException
BlockingIOError
BrokenPipeError
BufferError
BytesWarning
ChildProcessError
ConnectionAbortedError
ConnectionError
ConnectionRefusedError
ConnectionResetError
DeprecationWarning
EOFError
Ellipsis
EnvironmentError
Exception
False
FileExistsError
FileNotFoundError
FloatingPointError
FutureWarning
GeneratorExit
IOError
ImportError
ImportWarning
IndentationError
IndexError
InterruptedError
IsADirectoryError
KeyError
KeyboardInterrupt
LookupError
MemoryError
ModuleNotFoundError
NameError
None
NotADirectoryError
NotImplemented
NotImplementedError
OSError
OverflowError
PendingDeprecationWarning
PermissionError
ProcessLookupError
RecursionError
ReferenceError
ResourceWarning
RuntimeError
RuntimeWarning
StopAsyncIteration
StopIteration
SyntaxError
SyntaxWarning
SystemError
SystemExit
TabError
TimeoutError
True
TypeError
UnboundLocalError
UnicodeDecodeError
UnicodeEncodeError
UnicodeError
UnicodeTranslateError
UnicodeWarning
UserWarning
ValueError
Warning
WindowsError
ZeroDivisionError
__IPYTHON__
__build_class__
__debug__
__doc__
__import__
__loader__
__name__
__package__
__spec__
abs
all
any
ascii
bin
bool
breakpoint
bytearray
bytes
callable
chr
classmethod
compile
complex
copyright
credits
delattr
dict
dir
display
divmod
enumerate
eval
exec
filter
float
format
frozenset
get_ipython
getattr
globals
hasattr
hash
help
hex
id
input
int
isinstance
issubclass
iter
len
license
list
locals
map
max
memoryview
min
next
object
oct
open
ord
pow
print
property
range
repr
reversed
round
set
setattr
slice
sorted
staticmethod
str
sum
super
tuple
type
vars
zip

file module:

It contains the list of builtin variables and functions that can be used in the current file.

__add__
__class__
__contains__
__delattr__
__dir__
__doc__
__eq__
__format__
__ge__
__getattribute__
__getitem__
__getnewargs__
__gt__
__hash__
__init__
__init_subclass__
__iter__
__le__
__len__
__lt__
__mod__
__mul__
__ne__
__new__
__reduce__
__reduce_ex__
__repr__
__rmod__
__rmul__
__setattr__
__sizeof__
__str__
__subclasshook__
capitalize
casefold
center
count
encode
endswith
expandtabs
find
format
format_map
index
isalnum
isalpha
isascii
isdecimal
isdigit
isidentifier
islower
isnumeric
isprintable
isspace
istitle
isupper
join
ljust
lower
lstrip
maketrans
partition
replace
rfind
rindex
rjust
rpartition
rsplit
rstrip
split
splitlines
startswith
strip
swapcase
title
translate
upper
zfill

Private in modules:

Objects can be restricted to usage when running as a main module. They cannot be imported when importing the complete module using ‘ * ‘.

They start and end with double underscores, __

IN [2]

import prime_generator as pg

print(pg.__primeval)

stdout

IN [3]

from prime_generator import *

print(__primeval)

Error


Traceback (most recent call last):

  File "D:\Programming\Python\Jupyter Notebooks\Python_Programming_Notes\temp.py", line 3, in <module>

    print(__primeval)

NameError: name '__primeval' is not defined

globals(), locals() and reload()

globals - returns the list of objects that can be accessed globally from that point.

locals - returns the list of objects that can be accessed locally from that point.

reload - reloads the given module. (imported from impotlib module)

Syntax:

reload(module_name)

math:

This module contains list of all mathematical functions.

IN [3]

import math

print(*dir(math), sep='\n')

stdout

__doc__
__loader__
__name__
__package__
__spec__
acos
acosh
asin
asinh
atan
atan2
atanh
ceil
comb
copysign
cos
cosh
degrees
dist
e
erf
erfc
exp
expm1
fabs
factorial
floor
fmod
frexp
fsum
gamma
gcd
hypot
inf
isclose
isfinite
isinf
isnan
isqrt
ldexp
lgamma
log
log10
log1p
log2
modf
nan
perm
pi
pow
prod
radians
remainder
sin
sinh
sqrt
tan
tanh
tau
trunc

IN [5]

import math

print(math.pi/2)
print(math.asin(1))
# 1.570796... = pi/2

stdout

1.5707963267948966
1.5707963267948966

IN [6]

# 21.33 ceil - 22
# 21.33 floor - 21
# 21, 21.33, 22
print(math.ceil(21.33))
print(math.floor(21.33))

stdout

22
21

IN [10]

math.pow(2, 3) # 2 ** 3

$\mathit{^5P_2}$

IN [11]

math.perm(5, 2) # 5P2

$\mathit{^5C_2}$

IN [12]

math.comb(5, 2) # 5C2

cmath:

Like math, used to work with complex numbers.

IN [1]

import cmath

print(*dir(cmath), sep='\n')

stdout

__doc__
__loader__
__name__
__package__
__spec__
acos
acosh
asin
asinh
atan
atanh
cos
cosh
e
exp
inf
infj
isclose
isfinite
isinf
isnan
log
log10
nan
nanj
phase
pi
polar
rect
sin
sinh
sqrt
tan
tanh
tau

sys:

Work with program execution and system.

IN [2]

import sys

print(*dir(sys), sep='\n')

stdout

__breakpointhook__
__displayhook__
__doc__
__excepthook__
__interactivehook__
__loader__
__name__
__package__
__spec__
__stderr__
__stdin__
__stdout__
__unraisablehook__
_base_executable
_clear_type_cache
_current_frames
_debugmallocstats
_enablelegacywindowsfsencoding
_framework
_getframe
_git
_home
_xoptions
addaudithook
api_version
argv
audit
base_exec_prefix
base_prefix
breakpointhook
builtin_module_names
byteorder
call_tracing
callstats
copyright
displayhook
dllhandle
dont_write_bytecode
exc_info
excepthook
exec_prefix
executable
exit
flags
float_info
float_repr_style
get_asyncgen_hooks
get_coroutine_origin_tracking_depth
getallocatedblocks
getcheckinterval
getdefaultencoding
getfilesystemencodeerrors
getfilesystemencoding
getprofile
getrecursionlimit
getrefcount
getsizeof
getswitchinterval
gettrace
getwindowsversion
hash_info
hexversion
implementation
int_info
intern
is_finalizing
maxsize
maxunicode
meta_path
modules
path
path_hooks
path_importer_cache
platform
prefix
ps1
ps2
ps3
pycache_prefix
set_asyncgen_hooks
set_coroutine_origin_tracking_depth
setcheckinterval
setprofile
setrecursionlimit
setswitchinterval
settrace
stderr
stdin
stdout
thread_info
unraisablehook
version
version_info
warnoptions
winver

os:

works with operating system

IN [3]

import os
print(*dir(os), sep='\n')

stdout

DirEntry
F_OK
MutableMapping
O_APPEND
O_BINARY
O_CREAT
O_EXCL
O_NOINHERIT
O_RANDOM
O_RDONLY
O_RDWR
O_SEQUENTIAL
O_SHORT_LIVED
O_TEMPORARY
O_TEXT
O_TRUNC
O_WRONLY
P_DETACH
P_NOWAIT
P_NOWAITO
P_OVERLAY
P_WAIT
PathLike
R_OK
SEEK_CUR
SEEK_END
SEEK_SET
TMP_MAX
W_OK
X_OK
_AddedDllDirectory
_Environ
__all__
__builtins__
__cached__
__doc__
__file__
__loader__
__name__
__package__
__spec__
_check_methods
_execvpe
_exists
_exit
_fspath
_get_exports_list
_putenv
_unsetenv
_wrap_close
abc
abort
access
add_dll_directory
altsep
chdir
chmod
close
closerange
cpu_count
curdir
defpath
device_encoding
devnull
dup
dup2
environ
error
execl
execle
execlp
execlpe
execv
execve
execvp
execvpe
extsep
fdopen
fsdecode
fsencode
fspath
fstat
fsync
ftruncate
get_exec_path
get_handle_inheritable
get_inheritable
get_terminal_size
getcwd
getcwdb
getenv
getlogin
getpid
getppid
isatty
kill
linesep
link
listdir
lseek
lstat
makedirs
mkdir
name
open
pardir
path
pathsep
pipe
popen
putenv
read
readlink
remove
removedirs
rename
renames
replace
rmdir
scandir
sep
set_handle_inheritable
set_inheritable
spawnl
spawnle
spawnv
spawnve
st
startfile
stat
stat_result
statvfs_result
strerror
supports_bytes_environ
supports_dir_fd
supports_effective_ids
supports_fd
supports_follow_symlinks
symlink
sys
system
terminal_size
times
times_result
truncate
umask
uname_result
unlink
urandom
utime
waitpid
walk
write

itertools:

A module containing iterators for efficient looping

IN [4]

import itertools

print(*dir(itertools), sep='\n')

stdout

__doc__
__loader__
__name__
__package__
__spec__
_grouper
_tee
_tee_dataobject
accumulate
chain
combinations
combinations_with_replacement
compress
count
cycle
dropwhile
filterfalse
groupby
islice
permutations
product
repeat
starmap
takewhile
tee
zip_longest

Modules and Packages

import statement:

from statement:

Importing all the objects from the module:

as Keyword:

__name__:

dir method:

namespace:

Global, Local and Built-in Namespaces

Global:

Local:

Builtin:

Order of Search:

Packages:

Importing a module from package:

Import a specific object from a module:

Builtins:

__file__ module:

contents:

Private in modules:

globals(), locals() and reload()

math:

cmath:

sys:

os:

itertools:

name:

file module: