对列表中的值求和(python)

Question

大家好我无法尝试将列表中的所有值相加.我不确定这是否真的可行.

dL= list(csv.reader(input))
sL = dL [14247:14611]
a = [row[5] for row in sL[1:]] 
print a

这段代码是我到目前为止所产生的结果

['5.0', '0.0', '0.0', '0.0', '0.0', '1.6', '4.4', '14.0', '0.0', '0.0', '0.8', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.2', '0.0', '0.0', '0.0', '0.0', '95.6', '63.6', '0.0', '0.0', '0.0', '9.0', '0.0', '0.0', '0.0', '0.0', '20.2', '14.4', '1.6', '0.0', '7.6', '2.4', '0.0', '11.4', '0.0', '79.4', '60.4', '27.2', '', '1.8', '0.0', '0.0', '29.6', '67.6', '2.2', '0.0', '0.0', '0.0', '14.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '', '3.2', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '6.2', '0.0', '0.0', '0.0', '0.8', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.2', '11.8', '2.4', '0.0', '0.0', '0.0', '0.4', '16.8', '8.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '2.6', '27.2', '77.0', '0.2', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.2', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '9.2', '2.6', '0.0', '0.2', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.2', '0.0', '0.0', '0.0', '0.0', '0.2', '0.0', '0.0', '0.0', '0.0', '1.6', '0.0', '0.0', '0.0', '0.0', '0.0', '6.8', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '', '', '', '', '', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '37.8', '0.2', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0']

上面的列表不是键入的,而是由功能代码生成的.这会影响结果吗？

任何人都可以帮我告诉我如何解决这个问题,并在这个列表的代码中总结所有这些值.我相信我必须加入字符串这样做,但我不确定.您能告诉我是否可以将列表中的所有这些值相加,如果可以,我该怎么办？

编辑:

THANKS FOR ALL THE HELP GUYS 

Answer 1

我会用math.fsum更准确的总和:

>>> nums = ['5.0', '0.0', '0.0', '0.0', '0.0', '1.6', '4.4', '14.0', '0.0', '0.0', '0.8', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.2', '0.0', '0.0', '0.0', '0.0', '95.6', '63.6', '0.0', '0.0', '0.0', '9.0', '0.0', '0.0', '0.0', '0.0', '20.2', '14.4', '1.6', '0.0', '7.6', '2.4', '0.0', '11.4', '0.0', '79.4', '60.4', '27.2', '', '1.8', '0.0', '0.0', '29.6', '67.6', '2.2', '0.0', '0.0', '0.0', '14.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '', '3.2', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '6.2', '0.0', '0.0', '0.0', '0.8', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.2', '11.8', '2.4', '0.0', '0.0', '0.0', '0.4', '16.8', '8.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '2.6', '27.2', '77.0', '0.2', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.2', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '9.2', '2.6', '0.0', '0.2', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.2', '0.0', '0.0', '0.0', '0.0', '0.2', '0.0', '0.0', '0.0', '0.0', '1.6', '0.0', '0.0', '0.0', '0.0', '0.0', '6.8', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '', '', '', '', '', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '37.8', '0.2', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0', '0.0']
>>> from math import fsum
>>> fsum(float(n or 0.0) for n in nums)
749.8

相反

>>> sum(float(n or 0.0) for n in nums)
749.8000000000003

使用您的代码,一种更有效的方法,而无需一次将整个文件保存到内存中:

from itertools import islice
dL= csv.reader(input)
sL = islice(dL, 14247+1, 14611)    
a = [row[5] for row in sL] 
print fsum(float(n or 0.0) for n in a)