A Quick View of Pythonland

Now that you know the main steps to convert PERL programs into Python, let us look at Python from a new programmers’ angle.

Python core contains 32 keywords. Those words are special and cannot be used in as the names of variables. Also, Python comes with a set of commonly used functions. Those functions are shown below.

Python Keywords are Special Words

Keyword	Action
print	prints text on screen
and	logical ‘and’
or	logical ‘or’
not	logical ‘not’
True	logical True
False	logical False
is	tests equality
in	checks if an element is in a list or dictionary
del	deletes an element from a list or dictionary
if, else, elif	conditional statement
while	conditinal loop
for	loop
continue	skips current execution of loop
break	quits the loop prematurely
def	defines new function
return	returns value at the end of function
from, import	imports functions from file

Special words cannot be used as the names of variables.

Wrong code -

for = 1
in = 2
print for + in

Here is the Full List of Keywords

and, or, not

if, else, elif

while, for, continue, break, in

def, return
import, from, as

with, as (file)

in (list)

del (delete dictionary item, list item)

exec (shell command)

global, with, assert, pass, yield
except, class, raise, finally
is, lambda, try

The Same Keywords Listed Alphabetically

and del from not while
as elif global or with
assert else if pass yield
break except import print
class exec in raise
continue finally is return
def for lambda try

Built-in Functions in Python

Function - range()

The function range creates a list of integers.

print range(3)

print range(1,5)

print range(1,5,2)

Function - len()

This function gives the length of a list.

x=range(9,2,-2)
print len(x)

In the following code, the variable i goes from 0 to 3, because len(a)=4.

a=[0,1,2,3]
print “loop using list indices”
for i in range(len(a)):
print i,”a[i]+8=”,a[i]+8

Function - float()

The function float converts an integer to a floating point number.

x=1
y=float(x)
print x,y

Function - int()

The function int gives the integer part of a floating point number.

x=1.7
y=int(x)
print x,y

Function - str()

The function str convers a number into a string.

x=723
y=str(x)
print y[0]

All Built-in Functions

Python language includes 68 built-in functions.

Name	Action
help()	Invoke the built-in help system.
Number-related
abs()	Return the absolute value of a number.
pow()	Return power raised to a number.
round()	Return the rounded floating point value.
divmod()	Return a pair of numbers consisting of quotient and remainder when using integer division.
Creates Objects
ascii()	Return a string containing a printable representation of an object, but escape the non-ASCII characters.
bytearray()	Return a new array of bytes.
bytes()	Return a new “bytes” object.
chr()	Return the string representing a character.
complex()	Create a complex number or convert a string or number to a complex number.
dict()	Create a new dictionary.
enumerate()	Return an enumerate object.
frozenset()	Return a new frozenset object.
hash()	Return the hash value of the object.
id()	Return the “identity” of an object.
iter()	Return an iterator object.
list()	Return a list.
memoryview()	Return a “memory view” object created from the given argument.
object()	Return a new featureless object.
repr()	Return a string containing a printable representation of an object.
str()	Return a str version of object.
set()	Return a new set object.
slice()	Return a slice object.
tuple()	Return a tuple
type()	Return the type of an object.
Converts
bin()	Convert an integer number to a binary string.
bool()	Convert a value to a Boolean.
float()	Convert a string or a number to floating point.
format()	Convert a value to a “formatted” representation.
hex()	Convert an integer number to a hexadecimal string.
int()	Convert a number or string to an integer.
oct()	Convert an integer number to an octal string.
ord()	Return an integer representing the Unicode.
List operations
len()	Return the length (the number of items) of an object.
min()	Return the smallest item in an iterable.
max()	Return the largest item in an iterable.
sorted()	Return a new sorted list.
sum()	Sums the items of an iterable from left to right and returns the total.
Iterables
all()	Return True if all elements of the iterable are true (or if the iterable is empty).
any()	Return True if any element of the iterable is true. If the iterable is empty, return False.
callable()	Return True if the object argument appears callable, False if not.
map()	Return an iterator that applies function to every item of iterable, yielding the results.
filter()	Construct an iterator from elements of iterable for which function returns true.
zip()	Make an iterator that aggregates elements from each of the iterables.
range()	Return an iterable sequence.
next()	Retrieve the next item from the iterator.
reversed()	Return a reverse iterator.
I/O-related
dir()	Return the list of names in the current local scope.
open()	Open file and return a corresponding file object.
print()	Print objects to the stream.
input()	Reads a line from input, converts it to a string (stripping a trailing newline), and returns that.
Runs Code
compile()	Compile the source into a code or AST object.
eval()	The argument is parsed and evaluated as a Python expression.
exec()	Dynamic execution of Python code.
Other functions
classmethod()	Return a class method for the function.
getattr()	Return the value of the named attribute of an object.
setattr()	Assigns the value to the attribute.
delattr()	Deletes the named attribute of an object.
hasattr()	Return True if the name is one of the object’s attributes.
globals()	Return a dictionary representing the current global symbol table.
locals()	Update and return a dictionary representing the current local symbol table.
isinstance()	Return True if the object argument is an instance.
issubclass()	Return True if class is a subclass.
property()	Return a property attribute.
staticmethod()	Return a static method for function.
super()	Return a proxy object that delegates method calls to a parent or sibling class.
vars()	Return the _dict_ attribute for a module, class, instance, or any other object.
_import_()	This function is invoked by the import statement.

References

https://gist.github.com/mindful108/6412490
http://www.programiz.com/python-programming/keyword-list
https://learnpythonthehardway.org/book/ex37.html