How to Check list containing NaN

python

Solution

I think this makes sense because of your pulling `numpy` into scope indirectly via the star import.

>>> 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])

When you did

from matplotlib.pylab import *

it pulled in `numpy.sum`:

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

You can test that this `nan` object (`nan` isn't unique in general) is in a list via identity, but if you try it in an `array` it seems to test via equality, and `nan != nan`:

>>> nan == nan
False
>>> nan == nan, nan is nan
(False, True)
>>> nan in [nan]
True
>>> nan in np.array([nan])
False

You could use `np.isnan`:

>>> np.isnan([nan, nan])
array([ True,  True], dtype=bool)
>>> np.isnan([nan, nan]).any()
True

Problem

In my for loop, my code generates a list like this one: ``` list([0.0,0.0]/sum([0.0,0.0])) ``` The loop generates all sort of other number vectors but it also generates `[nan,nan]`, and to avoid it I tried to put in a conditional to prevent it like the one below, but it doesn't return true. ``` nan in list([0.0,0.0]/sum([0.0,0.0])) >>> False ``` Shouldn't it return true? Libraries I've loaded: ``` 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 ```

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