主要是做个笔记，以后可以方便梳理一下，尊重版权，特此申明下面信息均来自公司培训课PPT Nagiza F. Samatova, NC State Univ. All rights reserved
a_list = [1, '4', 9, 'a', 0, 4] squared_ints = [pow(e,2) for e in a_list if type(e) == int] print(squared_ints) # output:[1, 81, 0, 16] names=['Bob', 'JOHN', 'alice', 'bob', 'ALICE', 'J', 'BOB'] {name.title() for name in names if len(name) > 1} #output: {'Alice', 'Bob', 'John'}Python 字典(Dictionary) get() 函数返回指定键的值，如果值不在字典中返回默认值。default – 如果指定键的值不存在时，返回该默认值。
dict.get(key, default=None)
d = {'a':10, 'b': 34, 'A': 7, 'Z':3} mcase_frequency = { k.lower() : d.get(k.lower(), 0) + d.get(k.upper(), 0) for k in d.keys() } print(mcase_frequency) #output: {'a': 17, 'b': 34, 'z': 3}While–loops
input_str = ' ' while input_str != 'Quit' and input_str != 'Exit': input_str = input('Enter your name or type Quit or Exit:\n') input_str = input_str.title() print ('\tYou entered: ' + input_str) #output: Enter your name or type Quit or Exit: hello You entered: Hello Enter your name or type Quit or Exit: Quit You entered: Quitelse Clauses in the Loops Any code in else block will execute if the loop did not hit a break statement Useful when we are performing a search but no acceptable value was found and we need to raise an informative error
number_set = set (range(1, 6)) print ('\n\tSet of numbers: ' + str(number_set)) positive_flag = True for num in number_set: if num < 0: print ('\tFound a negative number: {}'.format(num)) break else: print ( '\tNumber is still positive...') positive_flag = False #output: Set of numbers: {1, 2, 3, 4, 5} Number is still positive...