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--- notes_pythons [2017/12/13 16:57]
gbdivers créée
+++ notes_pythons [2018/02/06 14:32] (Version actuelle)
gbdivers
@@ Ligne 1: / Ligne 1: @@
 ====== Notes Python ======
-===== Classes =====
+Sources :
+  * https://www.tutorialspoint.com/python3/index.htm
+Aller plus loin :
+  * https://medium.com/activewizards-machine-learning-company/top-15-python-libraries-for-data-science-in-in-2017-ab61b4f9b4a7
+===== Bases =====
+<code python>
+#!/usr/bin/python3
+# output
+print ("Hello, Python!")
+print(x, end=" ")  # Appends a space instead of a newline in Python 3
+# input
+x = input("something:")
+# raise exception
+raise IOError("file error") #this is the recommended syntax in Python 3
+</code>
+<code python>
+# Quotation in Python
+word = 'word'
+sentence = "This is a sentence."
+paragraph = """This is a paragraph. It is
+made up of multiple lines and sentences."""
+</code>
+===== Variable Types =====
+<code python>
+# Simple Assignment
+counter = 100          # An integer assignment
+miles   = 1000.0       # A floating point
+value   = 3e+26J       # A complex
+name    = "John"       # A string
+# Multiple Assignment
+a = b = c = 1
+a, b, c = 1, 2, "john"
+# deletion
+a, b, c = 1, 2, "john"
+</code>
+<code python>
+str = 'Hello World!'
+print (str)          # Prints complete string
+print (str[0])       # Prints first character of the string
+print (str[2:5])     # Prints characters starting from 3rd to 5th
+print (str[2:])      # Prints string starting from 3rd character
+print (str * 2)      # Prints string two times
+print (str + "TEST") # Prints concatenated string
+</code>
+<code python>
+list = [ 'abcd', 786 , 2.23, 'john', 70.2 ]
+tinylist = [123, 'john']
+print (list)          # Prints complete list
+print (list[0])       # Prints first element of the list
+print (list[1:3])     # Prints elements starting from 2nd till 3rd
+print (list[2:])      # Prints elements starting from 3rd element
+print (tinylist * 2)  # Prints list two times
+print (list + tinylist) # Prints concatenated lists
+</code>
+<code python>
+tuple = ( 'abcd', 786 , 2.23, 'john', 70.2  )
+tinytuple = (123, 'john')
+print (tuple)           # Prints complete tuple
+print (tuple[0])        # Prints first element of the tuple
+print (tuple[1:3])      # Prints elements starting from 2nd till 3rd
+print (tuple[2:])       # Prints elements starting from 3rd element
+print (tinytuple * 2)   # Prints tuple two times
+print (tuple + tinytuple) # Prints concatenated tuple
+</code>
+<code python>
+dict = {}
+dict['one'] = "This is one"
+dict[2]     = "This is two"
+tinydict = {'name': 'john','code':6734, 'dept': 'sales'}
+print (dict['one'])       # Prints value for 'one' key
+print (dict[2])           # Prints value for 2 key
+print (tinydict)          # Prints complete dictionary
+print (tinydict.keys())   # Prints all the keys
+print (tinydict.values()) # Prints all the values
+</code>
+<code python>
+#Data Type Conversion
+int(x [,base]) #Converts x to an integer. The base specifies the base if x is a string.
+float(x) # Converts x to a floating-point number.
+complex(real [,imag]) # Creates a complex number.
+str(x) # Converts object x to a string representation.
+repr(x) # Converts object x to an expression string.
+eval(str) # Evaluates a string and returns an object.
+tuple(s) # Converts s to a tuple.
+list(s) # Converts s to a list.
+set(s) # Converts s to a set.
+dict(d) # Creates a dictionary. d must be a sequence of (key,value) tuples.
+frozenset(s) # Converts s to a frozen set.
+chr(x) # Converts an integer to a character.
+unichr(x) # Converts an integer to a Unicode character.
+ord(x) # Converts a single character to its integer value.
+hex(x) # Converts an integer to a hexadecimal string.
+oct(x) # Converts an integer to an octal string.
+</code>
+===== Basic Operators =====
+<code python>
+# Python Arithmetic Operators
+c = a % b  # Modulus
+c = a ** b # Exponent
+c = a // b # Floor Division
+# Python Membership Operators
+x in y
+x not in y
+# Python Identity Operators
+x is y
+x is not y
+</code>
+===== Decision Making =====
+<code python>
+# if statement
+if expression:
+   statement(s)
+# if else statement
+if expression:
+   statement(s)
+else:
+   statement(s)
+# nested if statements
+if expression1:
+   statement(s)
+elif expression:
+   statement(s)
+else:
+   statement(s)
+# Single Statement if
+if ( var  == 100 ) : print ("Value of expression is 100")
+</code>
+===== Decision Making =====
+<code python>
+# while loop
+while expression:
+   statement(s)
+while count < 5:
+   count = count + 1
+else:
+   print (count, " is not less than 5")
+# for loop
+for iterating_var in sequence:
+   statements(s)
+>>> range(5)
+range(0, 5)
+>>> list(range(5))
+[0, 1, 2, 3, 4]
+fruits = ['banana', 'apple',  'mango']
+for index in range(len(fruits)):
+   print ('Current fruit :', fruits[index])
+for num in numbers:
+   if num%2 == 0:
+      print ('the list contains an even number')
+      break
+else:
+   print ('the list doesnot contain even number')
+# Loop Control Statements
+break
+continue
+pass
+</code>
+<code python>
+# Iterators
+list = [1,2,3,4]
+it = iter(list) # this builds an iterator object
+print (next(it)) #prints next available element in iterator
+# Iterator object can be traversed using regular for statement
+for x in it:
+   print (x, end=" ")
+# or using next() function
+while True:
+   try:
+      print (next(it))
+   except StopIteration:
+      sys.exit() #you have to import sys module for this
+</code>
+<code python>
+# Generators
+import sys
+def fibonacci(n): #generator function
+   a, b, counter = 0, 1, 0
+   while True:
+      if (counter > n):
+         return
+      yield a
+      a, b = b, a + b
+      counter += 1
+f = fibonacci(5) #f is iterator object
+while True:
+   try:
+      print (next(f), end=" ")
+   except StopIteration:
+      sys.exit()
+</code>
+===== Numbers =====
+<code python>
+number = 1 # int
+number = 1.2 # float
+number = -32.54e100
+number = 1 + 2J #complex
+number = 0xA0F #Hexa-decimal = 2575
+number = 0o37 #Octal = 31
+# Number Type Conversion
+int(x)
+long(x)
+float(x)
+complex(x)
+complex(x, y)
+# Mathematical Functions
+abs(x)
+ceil(x)
+cmp(x, y) # Deprecated
+exp(x)
+fabs(x)
+floor(x)
+log(x)
+log10(x)
+max(x1, x2,...)
+min(x1, x2,...)
+modf(x)
+pow(x, y)
+round(x [,n])
+sqrt(x)
+# Random Number Functions
+choice(seq)
+randrange ([start,] stop [,step])
+random()
+seed([x])
+shuffle(lst)
+uniform(x, y)
+# Trigonometric Functions
+acos(x)
+asin(x)
+atan(x)
+atan2(y, x)
+cos(x)
+hypot(x, y)
+sin(x)
+tan(x)
+degrees(x)
+radians(x)
+# Mathematical Constants
+pi
+e
+</code>
+===== Strings =====
+<code python>
+var1 = 'Hello World!'
+var2 = "Python Programming"
+# substrings
+var1[0]
+var2[1:5]
+# String Special Operators
+a + b
+a * n
+a[n] # slice
+a[n:m] # range slice
+a in b
+a in not b
+r'...' # raw string
+R'...' # raw string
+</code>
+<code python>
+# String Formatting Operator
+print ("My name is %s and weight is %d kg!" % ('Zara', 21))
+%c character
+%s string conversion via str() prior to formatting
+%i signed decimal integer
+%d signed decimal integer
+%u unsigned decimal integer
+%o octal integer
+%x hexadecimal integer (lowercase letters)
+%X hexadecimal integer (UPPERcase letters)
+%e exponential notation (with lowercase 'e')
+%E exponential notation (with UPPERcase 'E')
+%f floating point real number
+%g the shorter of %f and %e
+%G the shorter of %f and %E
+*     argument specifies width or precision
+-     left justification
++     display the sign
+<sp>  leave a blank space before a positive number
+#     add the octal leading zero ( '0' ) or hexadecimal leading '0x' or '0X',
+      depending on whether 'x' or 'X' were used.
+     pad from left with zeros (instead of spaces)
+%     '%%' leaves you with a single literal '%'
+(var) mapping variable (dictionary arguments)
+m.n.  m is the minimum total width and n is the number of digits to display
+      after the decimal point (if appl.)
+# Triple Quotes
+para_str = """this is a long string that is made up of
+several lines and non-printable characters such as
+TAB ( \t ) and they will show up that way when displayed.
+the variable assignment will also show up.
+"""
+</code>
+<code python>
+# Unicode String
+capitalize()
+center(width, fillchar)
+count(str, beg = 0,end = len(string))
+decode(encoding = 'UTF-8', errors = 'strict')
+encode(encoding = 'UTF-8', errors = 'strict')
+endswith(suffix, beg = 0, end = len(string))
+expandtabs(tabsize = 8)
+find(str, beg = 0 end = len(string))
+index(str, beg = 0, end = len(string))
+isalnum()
+isalpha()
+isdigit()
+islower()
+isnumeric()
+isspace()
+istitle()
+isupper()
+join(seq)
+len(string)
+ljust(width[, fillchar])
+lower()
+lstrip()
+maketrans()
+max(str)
+min(str)
+replace(old, new [, max])
+rfind(str, beg = 0,end = len(string))
+rindex( str, beg = 0, end = len(string))
+rjust(width,[, fillchar])
+rstrip()
+split(str="", num=string.count(str))
+splitlines( num=string.count('\n'))
+startswith(str, beg=0,end=len(string))
+strip([chars])
+swapcase()
+title()
+translate(table, deletechars="")
+upper()
+zfill (width)
+isdecimal()
+</code>
+===== List =====
+<code python>
+list1 = ['physics', 'chemistry', 1997, 2000]
+list2 = [1, 2, 3, 4, 5 ]
+list3 = ["a", "b", "c", "d"]
+# get
+list1[0]
+list2[1:5]
+L[2]
+L[-2]
+L[1:]
+# set
+list[2] = 2001
+# remove
+del list[2]
+# Basic List Operations
+len([1, 2, 3])          # length
+[1, 2, 3] + [4, 5, 6]   # concatenation
+['Hi!'] * 4             # repetition
+in [1, 2, 3]          # membership
+for x in [1,2,3] : print (x,end = ' ')
+# Built-in List Functions and Methods
+cmp(list1, list2) # obsolete
+len(list)
+max(list)
+min(list)
+list(seq)
+list.append(obj)
+list.count(obj)
+list.extend(seq)
+list.index(obj)
+list.insert(index, obj)
+list.pop(obj = list[-1])
+list.remove(obj)
+list.reverse()
+list.sort([func])
+</code>
+===== Tuples =====
+<code python>
+tup1 = ('physics', 'chemistry', 1997, 2000)
+tup2 = (1, 2, 3, 4, 5 )
+tup3 = "a", "b", "c", "d"
+tup1 = (); # empty tuple
+tup1 = (50,)
+# Accessing Values in Tuples
+tup1[0]
+tup2[1:5]
+# Updating Tuples
+tup3 = tup1 + tup2 # concatenate
+del tup
+# Basic Tuples Operations
+len((1, 2, 3))	        # Length
+(1, 2, 3) + (4, 5, 6)   # concatenation
+('Hi!',) * 4            # repetition
+in (1, 2, 3)          # membership
+for x in (1,2,3) : print (x, end = ' ')
+# Indexing, Slicing, and Matrixes
+T[2]
+T[-2]
+T[1:]
+# Built-in Tuple Functions
+cmp(tuple1, tuple2)
+len(tuple)
+max(tuple)
+min(tuple)
+tuple(seq)
+</code>
+===== Dictionary =====
+<code python>
+dict = {'Name': 'Zara', 'Age': 7, 'Class': 'First'}
+dict['Age']
+# Updating Dictionary
+dict['Age'] = 8; # update existing entry
+dict['School'] = "DPS School" # Add new entry
+# Delete Dictionary Elements
+del dict['Name'] # remove entry with key 'Name'
+dict.clear()     # remove all entries in dict
+del dict         # delete entire dictionary
+# Built-in Dictionary Functions and Methods
+cmp(dict1, dict2)
+len(dict)
+str(dict)
+type(variable)
+dict.clear()
+dict.copy()
+dict.fromkeys()
+dict.get(key, default=None)
+dict.has_key(key)
+dict.items()
+dict.keys()
+dict.setdefault(key, default = None)
+dict.update(dict2)
+dict.values()
+</code>
+===== Date and time =====
+<code python>
+import time;  # This is required to include time module.
+ticks = time.time()
+print ("Number of ticks since 12:00am, January 1, 1970:", ticks)
+> time.struct_time(tm_year = 2016, tm_mon = 2, tm_mday = 15, tm_hour = 9,
+   tm_min = 29, tm_sec = 2, tm_wday = 0, tm_yday = 46, tm_isdst = 0)
+# Getting current time
+localtime = time.localtime(time.time())
+localtime = time.asctime( time.localtime(time.time()) ) # formatted
+# The time Module
+time.altzone
+time.asctime([tupletime])
+time.clock( )
+time.ctime([secs])
+time.gmtime([secs])
+time.localtime([secs])
+time.mktime(tupletime)
+time.sleep(secs)
+time.strftime(fmt[,tupletime])
+time.strptime(str,fmt = '%a %b %d %H:%M:%S %Y')
+time.time( )
+time.timezone
+time.tzname
+</code>
+<code python>
+import calendar
+cal = calendar.month(2016, 2)
+print ("Here is the calendar:")
+print (cal)
+# affiche:
+Here is the calendar:
+   February 2016
+Mo Tu We Th Fr Sa Su
+  2  3  4  5  6  7
+  9 10 11 12 13 14
+16 17 18 19 20 21
+23 24 25 26 27 28
+
+# The calendar Module
+calendar.calendar(year,w = 2,l = 1,c = 6)
+calendar.firstweekday( )
+calendar.isleap(year)
+calendar.leapdays(y1,y2)
+calendar.month(year,month,w = 2,l = 1)
+calendar.monthcalendar(year,month)
+calendar.monthrange(year,month)
+calendar.prcal(year,w = 2,l = 1,c = 6)
+calendar.prmonth(year,month,w = 2,l = 1)
+calendar.setfirstweekday(weekday)
+calendar.timegm(tupletime)
+calendar.weekday(year,month,day)
+</code>
+===== Functions =====
+<code python>
+# Syntax
+def functionname( parameters ):
+   "function_docstring"
+   function_suite
+   return [expression]
+# Function definition is here
+def printme( str ):
+   "This prints a passed string into this function"
+   print (str)
+   return
+# Now you can call printme function
+printme("This is first call to the user defined function!")
+printme("Again second call to the same function")
+# All parameters (arguments) in the Python language are passed by reference.
+# Required Arguments
+def printme( str ):
+# Keyword Arguments
+printme( str = "My string")
+# Default Arguments
+def printinfo( name, age = 35 ):
+#Variable-length Arguments
+def functionname([formal_args,] *var_args_tuple ):
+   "function_docstring"
+   function_suite
+   return [expression]
+# Function definition is here
+def printinfo( arg1, *vartuple ):
+   "This prints a variable passed arguments"
+   print ("Output is: ")
+   print (arg1)
+   for var in vartuple:
+      print (var)
+   return
+# Now you can call printinfo function
+printinfo( 10 )
+printinfo( 70, 60, 50 )
+#The return Statement
+def sum( arg1, arg2 ):
+   return total
+total = sum( 10, 20 )
+</code>
+<code python>
+# The Anonymous Functions
+lambda [arg1 [,arg2,.....argn]]:expression
+# Function definition is here
+sum = lambda arg1, arg2: arg1 + arg2
+# Now you can call sum as a function
+print ("Value of total : ", sum( 10, 20 ))
+print ("Value of total : ", sum( 20, 20 ))
+</code>
+===== Modules =====
+<code python>
+# The import Statement
+import module1[, module2[,... moduleN]
+# support.py
+def print_func( par ):
+   print "Hello : ", par
+   return
+#usage
+import support
+support.print_func("Zara")
+</code>
+<code python>
+# The from...import Statement
+from modname import name1[, name2[, ... nameN]]
+# fib.py
+def fib(n): # return Fibonacci series up to n
+   result = []
+   a, b = 0, 1
+   while b < n:
+      result.append(b)
+      a, b = b, a + b
+   return result
+#usage
+from fib import fib
+</code>
+<code python>
+# The from...import * Statement
+from modname import *
+</code>
+<code python>
+# Executing Modules as Scripts
+#!/usr/bin/python3
+# Fibonacci numbers module
+def fib(n): # return Fibonacci series up to n
+   result = []
+   a, b = 0, 1
+   while b < n:
+      result.append(b)
+      a, b = b, a + b
+   return result
+if __name__ == "__main__":
+   f = fib(100)
+   print(f)
+</code>
+the following sequences
+  - The current directory.
+  - If the module is not found, Python then searches each directory in the shell variable PYTHONPATH.
+  - If all else fails, Python checks the default path. On UNIX, this default path is normally /usr/local/lib/python3/.
+The sys.path variable contains the current directory, PYTHONPATH, and the installation-dependent default.
+<code python>
+dir(plugin)
+locals()
+globals()
+reload(plugin)
+</code>
+<code python>
+# Packages in Python
+Phone/Pots.py
+Phone/IsDn.py
+Phone/G3.py
+# Phone/__init__.py
+from Pots import Pots
+from Isdn import Isdn
+from G3 import G3
+# uses
+import Phone
+Phone.Pots()
+Phone.Isdn()
+Phone.G3()
+</code>
+===== Files I/O =====
+<code python>
+#Printing to the Screen
+print ("Python is really a great language,", "isn't it?")
+#The input Function
+x = input("something:")
+</code>
+<code python>
+# The open Function
+file object = open(file_name [, access_mode][, buffering])
+access_mode = r/r+/w/w+/a, b
+# Open a file
+fileObject.close();
+fo = open("foo.txt", "wb")
+print ("Name of the file: ", fo.name)
+print ("Closed or not : ", fo.closed)
+print ("Opening mode : ", fo.mode)
+fo.close()
+# The write() Method
+fileObject.write(string);
+fo = open("foo.txt", "w")
+fo.write( "Python is a great language.\nYeah its great!!\n")
+fo.close()
+# The read() Method
+fileObject.read([count]);
+fo = open("foo.txt", "r+")
+str = fo.read(10)
+print ("Read String is : ", str)
+fo.close()
+# File Positions
+position = fo.tell()
+position = fo.seek(0, 0)
+# Renaming and Deleting Files
+os.rename(current_file_name, new_file_name)
+os.remove(file_name)
+os.mkdir(dir_name)
+os.chdir(dire_name)
+os.getcwd()
+os.rmdir(dir_name)
+</code>
+===== Exceptions Handling =====
+<code python>
+# Standard Exceptions
+Exception # Base class for all exceptions
+StopIteration # Raised when the next() method of an iterator does not point to any object.
+SystemExit # Raised by the sys.exit() function.
+StandardError # Base class for all built-in exceptions except StopIteration and SystemExit.
+ArithmeticError # Base class for all errors that occur for numeric calculation.
+OverflowError # Raised when a calculation exceeds maximum limit for a numeric type.
+FloatingPointError # Raised when a floating point calculation fails.
+ZeroDivisonError # Raised when division or modulo by zero takes place for all numeric types.
+AssertionError # Raised in case of failure of the Assert statement.
+AttributeError # Raised in case of failure of attribute reference or assignment.
+EOFError # Raised when there is no input from either the raw_input() or input() function and
+         # the end of file is reached.
+ImportError # Raised when an import statement fails.
+KeyboardInterrupt # Raised when the user interrupts program execution, usually by pressing Ctrl+c.
+LookupError # Base class for all lookup errors.
+IndexError # Raised when an index is not found in a sequence.
+KeyError # Raised when the specified key is not found in the dictionary.
+NameError # Raised when an identifier is not found in the local or global namespace.
+UnboundLocalError # Raised when trying to access a local variable in a function or method
+                  # but no value has been assigned to it.
+EnvironmentError # Base class for all exceptions that occur outside the Python environment.
+IOError # Raised when an input/ output operation fails, such as the print statement or the
+        # open() function when trying to open a file that does not exist.
+OSError # Raised for operating system-related errors.
+SyntaxError # Raised when there is an error in Python syntax.
+IndentationError # Raised when indentation is not specified properly.
+SystemError # Raised when the interpreter finds an internal problem, but when this error
+            # is encountered the Python interpreter does not exit.
+SystemExit # Raised when Python interpreter is quit by using the sys.exit() function.
+           # If not handled in the code, causes the interpreter to exit.
+TypeError # Raised when an operation or function is attempted that is invalid for the specified data type.
+ValueError # Raised when the built-in function for a data type has the valid type of arguments,
+           # but the arguments have invalid values specified.
+RuntimeError # Raised when a generated error does not fall into any category.
+NotImplementedError # Raised when an abstract method that needs to be implemented in an
+                    # inherited class is not actually implemented.
+</code>
+<code python>
+# assert Statement
+assert Expression[, Arguments]
+assert (Temperature >= 0), "Colder than absolute zero!"
+# Handling an exception
+try:
+   fh = open("testfile", "w")
+   fh.write("This is my test file for exception handling!!")
+except IOError:
+   print ("Error: can\'t find file or read data")
+except AssertionError, SystemExit:
+   print ("Error: multiple exceptions")
+except ValueError as Argument:
+   print ("The argument does not contain numbers\n", Argument)
+except:
+   print ("Error: all exceptions")
+else:
+   print ("Written content in the file successfully")
+finally:
+   fh.close()
+# Raising an Exception
+raise Exception(level)
+# User-Defined Exceptions
+class Networkerror(RuntimeError):
+   def __init__(self, arg):
+      self.args = arg
+try:
+   raise Networkerror("Bad hostname")
+except Networkerror,e:
+   print e.args
+</code>
+===== Objects =====
+<code python>
+</code>
 <code python>
@@ Ligne 28: / Ligne 920: @@
 emp2.displayEmployee()
 print "Total Employee %d" % Employee.empCount
+</code>
-// Built-In Class Attributes
+<code python>
+# Built-In Class Attributes
 print "Employee.__doc__:", Employee.__doc__
 print "Employee.__name__:", Employee.__name__
@@ Ligne 36: / Ligne 929: @@
 print "Employee.__bases__:", Employee.__bases__
 print "Employee.__dict__:", Employee.__dict__
+</code>
-// Destroying Objects (Garbage Collection)
+<code python>
-del emp1
+# Class Inheritance
-// Class Inheritance
-#!/usr/bin/python
 class Parent:        # define parent class
    parentAttr = 100
@@ Ligne 69: / Ligne 959: @@
 c.setAttr(200)       # again call parent's method
 c.getAttr()          # again call parent's method
+</code>
+<code python>
-// Overriding Methods
+# Overriding Methods
-#!/usr/bin/python
 class Parent:        # define parent class
    def myMethod(self):

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