以下是一些Python實用技巧和工具,希望能對大家有所幫助。
交換變量
x = 6y = 5x, y = y, xprint x>>> 5print y>>> 6
if 語句在行內
print "Hello" if True else "World">>> Hello
連接
下面的最后一種方式在綁定兩個不同類型的對象時顯得很cool。
nfc = ["Packers", "49ers"]afc = ["Ravens", "Patriots"]print nfc + afc>>> ['Packers', '49ers', 'Ravens', 'Patriots']print str(1) + " world">>> 1 worldprint `1` + " world">>> 1 worldprint 1, "world">>> 1 worldprint nfc, 1>>> ['Packers', '49ers'] 1
數字技巧
#除后向下取整
print 5.0//2>>> 2# 2的5次方print 2**5>> 32
注意浮點數的除法
print .3/.1>>> 2.9999999999999996print .3//.1>>> 2.0
數值比較
這是我見過諸多語言中很少有的如此棒的簡便法
x = 2if 3 > x > 1:print x>>> 2if 1 < x > 0:print x>>> 2
同時迭代兩個列表
nfc = ["Packers", "49ers"]afc = ["Ravens", "Patriots"]for teama, teamb in zip(nfc, afc):print teama + " vs. " + teamb>>> Packers vs. Ravens>>> 49ers vs. Patriots
帶索引的列表迭代
teams = ["Packers", "49ers", "Ravens", "Patriots"]for index, team in enumerate(teams):print index, team>>> 0 Packers>>> 1 49ers>>> 2 Ravens>>> 3 Patriots
列表推導式
已知一個列表,我們可以刷選出偶數列表方法:
numbers = [1,2,3,4,5,6]even = []for number in numbers:if number%2 == 0:even.append(number)
轉變成如下:
numbers = [1,2,3,4,5,6]even = [number for number in numbers if number%2 == 0]
是不是很牛呢,哈哈。
字典推導
和列表推導類似,字典可以做同樣的工作:
teams = ["Packers", "49ers", "Ravens", "Patriots"]print {key: value for value, key in enumerate(teams)}>>> {'49ers': 1, 'Ravens': 2, 'Patriots': 3, 'Packers': 0}
初始化列表的值
items = [0]*3print items>>> [0,0,0]
列表轉換為字符串
teams = ["Packers", "49ers", "Ravens", "Patriots"]print ", ".join(teams)>>> 'Packers, 49ers, Ravens, Patriots'
從字典中獲取元素
我承認try/except代碼并不雅致,不過這里有一種簡單方法,嘗試在字典中查找key,如果沒有找到對應的alue將用第二個參數設為其變量值。
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