python 快速入门

导入

#from dir1 import test

#import dir1.test as test

列表推到：

b3 =[x for x in xing if x in ming] print(b3)

 li = [1, 2, 3, 4] [elem*2 for elem in li] 

print [x*y for x in [1,2,3] for y in  [1,2,3]]

zip:

l1=[1,2,3,4] l2=[2,4,6,7] print(zip(l1,l2)) for (a,b)in zip(l1,l2):     print((a,b))

enumerate:

testStr = 'cainiao' for (offset,item) in enumerate(testStr):   print (item,'appears at offset:',offset)

has_key was removed from python3.x and use （key in dict)

http://blog.csdn.net/dingyaguang117/article/details/7170881

http://www.cainiao8.com/python/basic/python_11_for.html

循环组合

while i<len(xing):     print ([xing[i]+ming[i]])     i=i+1

xing=['wang','li','zhang',"liu"] for i in range(len(xing)):      print (i, xing[i])

for i in range(1, 5):     print i else:     print 'The for loop is over'

while True:     s = raw_input('Enter something : ')     if s == 'quit':         break     if len(s) < 3:         continue     print 'Input is of sufficient length'

快速生成词典

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list1 =['a','b','c','d'] d = {} list2=[24, 53, 26, 9] i=0 while i <len(list1) :     d[list1[i]]=list2[i]     i=i+1 print(d)

list1 =['a','b','c','d'] d = {'a':24, 'b':53 ,'c':26, 'd':9} new_list = [d[k] for k in list1] assert new_list == [24, 53, 26, 9]

定位字符的位置

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def read_line(line):     sample = {}     n = len(line)     for i in range(n):       if line[i]!='0':         sample[i] = int(line[i])         '''sample[i] is key  int(line[i]) means make it int type'''         print(sample)     return sample print(read_line('01101001'))

字符个数统计

d={} x_string='Pythonhello' for x in x_string:     key=x.rstrip()     if key in d:         d[key]=d[key]+1     else:         d[key] = 1 for k,v in d.items():     print("%s=%s"%(k,v))

http://www.cainiao8.com/python/basic/python_07_dictionary_tuple.html

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导入

'''import hello name_pr(q,b,c) a=hello.name_pr(2,3,4) print(a)''

引用计算单词数目

1. import sys  
2. import string  
3. #import collections  
5. if len(sys.argv) == 1 or sys.argv[1] in {"-h", "--help"}:  
6.  print("usage: uniqueword filename_1 filename_2 ... filename_n")  
7.  sys.exit()  
8. else:  
9.  words = {}   
10.  # words = collections.defaultdict(int)  
11.  strip = string.whitespace + string.punctuation + string.digits + "\"'"  
12.  for filename in sys.argv[1:]:  
13.   for line in open(filename):  
14.    for word in line.split():  
15.     word = word.strip(strip)  
16.     if len(word) >= 2:  
17.      words[word] = words.get(word, 0) + 1  
18.      # words[word] += 1  
19.  for word in sorted(words):  
20.   print("'{0}' occurs {1} times".format(word,words[word]))  可以使用get()方法来访问字典项,get()方法还可以设置第二个参数，如果b不存在，可以将第二个参数做为默认值返回。

高级函数

http://www.cainiao8.com/python/basic/python_13_function_adv.html

迭代器

#iterator testDict = {'name':'Chen  Zhe','gender':'male'} testIter = iter(testDict) print testIter.next()

异常处理

http://www.cainiao8.com/python/basic/python_16_exception.html

字典(dict)转为字符串(string)

我们可以比较容易的将字典(dict)类型转为字符串(string)类型。

通过遍历dict中的所有元素就可以实现字典到字符串的转换：

for key, value in sample_dic.items():
    print "\"%s\":\"%s\"" % (key, value)

字符串(string)转为字典(dict)

如何将一个字符串(string)转为字典(dict)呢?

其实也很简单，只要用 eval()或exec() 函数就可以实现了。

>>> a = "{'a': 'hi', 'b': 'there'}"
>>> b = eval(a)
>>> b
{'a': 'hi', 'b': 'there'}
>>> exec ("c=" + a)
>>> c
{'a': 'hi', 'b': 'there'}
>>> 

http://www.pythonclub.org/python-hacks/start