馮唐--python學習日記(1)

1、python是大小寫敏感的語言

2、在書寫函數時需定義

例：

def  functionname(parameter1[,]):

3、書寫控制塊的時候需要代碼縮進一個Tab鍵值，一個縮進層等于四個空格，八個空格等于一個制表符。

4、當遇到非縮進代碼行時，函數定義結束。

5、控制語句后面都需跟冒號（:），并且控制語句中的語句需要縮進一層。

例（1）：

>>> def MyFunction(MyNember):
...     if(MyNember == 855):
...             print "right"
...     else:
...             print "worst"
...
>>> MyFunction(5)
worst
>>> MyFunction(855)
right
>>>

例（2）：

>>> FoodTuple=("Spam","Egg","Sausage")
>>> FoodTuple=list(FoodTuple)
>>> FoodList
['Spam', 'Egg', 'Sausage']
>>> FoodList[2]
'Sausage'
>>> FoodList[2]="Spam"
>>> NewFoodTuple=tuple(FoodList)
>>> NewFoodTuple
('Spam', 'Egg', 'Spam')
>>>

例（3）：

>>> PhoneDict=
>>> EmptyDict={}
>>> PhoneDict["bob"]
'555-1212'
>>> PhoneDict["cindy"]="867-5309"
>>> print "phone list:",PhoneDict
phone list: {'bob': '555-1212', 'cindy': '867-5309', 'fred': '555-3345'}
>>> PhoneDict["luke"]
Traceback (most recent call last):
  File "", line 1, in ?
KeyError: 'luke'
>>> PhoneDict.get("joe","unknown")
'unknown'
>>> PhoneDict.get("bob","unknown")
'555-1212'
>>>

>>> DialAJoe=PhoneDict.get("joe",None)
>>> DialAJoe
>>> print DialAJoe
None
>>> DialAJoe=PhoneDict.get("bob",None)
>>> print DialAJoe
555-1212
>>>

6、list(),tuple()可以轉換元組和列表

list為列表，tuple為元組

7、變量，常量等基本元素單位不定義就可以使用。和其他的語言不同。

例（4）：

>>> import string
>>> def CountWords(Text):
...     WordCount={}
...     CurrentWord=""
...     Text = Text+"."
...     PlecesOfWords = string.letters + "'-"
...     for CharacterIndex in range(0,len(Text)):
...             CurrentCharacter = Text[CharacterIndex]
...             if (PlecesOfWords.find(CurrentCharacter)!= -1):
...                     CurrentWord = CurrentWord + CurrentCharacter
...             else:
...                     if(CurrentWord!=""):
...                             CurrentWord = string.lower(CurrentWord)
...                             CurrentCount = WordCount.get(CurrentWord,0)
...                             WordCount[CurrentWord]=CurrentCount+1
...             CurrentWord = ""
...     return(WordCount)
...     if(__name__=="__main__"):
...             TextFile = open("poem.txt","r")
...             Text = TextFile.read()
...             TextFile.close()
...             WordCount = CountWords(Text)
...             SortedWords = WordCount.keys()
...             SortedWords.sort()
...             for Word in SortedWords:
...                     print Word,WordCount[Word]
...
例（5）：

>>> import math
>>> class Point:
 def __init__(self,X,Y):
  self.X = X
  self.Y = Y
 def DistanceToPoint(self,OtherPoint):
  "Returns the distance from this point to another"
  SumOfSquares = ((self.X-OtherPoint.X)**2)+
    ((self.Y-OtherPoint.Y)**2)
  return math.sqrt(SumOfSquares)
 def IsInsideCircle(self,Center,Radius):
  """Return 1 if this point is inside the circle,
  0 otherwise"""
  if (self.DistanceToPoint(Center)<
   return 1
  else:
   return 0

>>> PointA= Point(3,5)
>>> PointB= Point(-4,-4)
>>> print "A to B:",PointA.DistanceToPoint(PointB)
A to B: 11.401754251
>>> print "B to A:",PointB.DistanceToPoint(PointA)
B to A: 11.401754251
>>> CircleCenter = Point(3,3)
>>> print "A in circle:",PointA.IsInsideCircle(CircleCenter,5)
A in circle: 1
>>> print "B in circle:",PointB.IsInsideCircle(CircleCenter,5)
B in circle: 0
>>>

原文轉自：http://www.anti-gravitydesign.com