如何检查包含NaN的列表

Question

在我的for循环中，我的代码会生成一个像这样的列表：

list([0.0,0.0]/sum([0.0,0.0]))

循环生成所有类型的其他数字向量，但它也生成[nan,nan]，并且为了避免它，我试图放入条件以防止它像下面那样，但它不会返回true。

nan in list([0.0,0.0]/sum([0.0,0.0]))
>>> False

不应该归还吗？

我已加载的库：

import PerformanceAnalytics as perf
import DataAnalyticsHelpers
import DataHelpers as data
import OptimizationHelpers as optim
from matplotlib.pylab import *
from pandas.io.data import DataReader
from datetime import datetime,date,time
import tradingWithPython as twp
import tradingWithPython.lib.yahooFinance as data_downloader # used to get data from yahoo finance
import pandas as pd # as always.
import numpy as np
import zipline as zp
from scipy.optimize import minimize
from itertools import product, combinations
import time
from math import isnan

Answer 1

我认为这是有道理的，因为您通过星号导入间接地将numpy拉入范围。

>>> import numpy as np
>>> [0.0,0.0]/0
Traceback (most recent call last):
  File "<ipython-input-3-aae9e30b3430>", line 1, in <module>
    [0.0,0.0]/0
TypeError: unsupported operand type(s) for /: 'list' and 'int'

>>> [0.0,0.0]/np.float64(0)
array([ nan,  nan])

当你做了

from matplotlib.pylab import *

它进入了numpy.sum：

>>> from matplotlib.pylab import *
>>> sum is np.sum
True
>>> [0.0,0.0]/sum([0.0, 0.0])
array([ nan,  nan])

您可以测试此 nan对象（nan一般不是唯一的）是通过标识列在列表中，但如果您在{{{它似乎通过平等来测试，array：

nan != nan

您可以使用>>> nan == nan False >>> nan == nan, nan is nan (False, True) >>> nan in [nan] True >>> nan in np.array([nan]) False ：

np.isnan

Answer 2

您应该使用math模块。

>>> import math
>>> math.isnan(item)

Answer 3

也许这就是您要寻找的...

a = [2,3,np.nan]
b = True if True in np.isnan(np.array(a)) else False
print(b)