Home/ Questions/What is the: ''Cannot mask with non-boolean array containing NA / NaN values'' problem, and how to solve it?
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Kylie Roberts
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Asked: 2022-05-18T18:44:24+00:00 In:

What is the: ”Cannot mask with non-boolean array containing NA / NaN values” problem, and how to solve it?

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I encountered the following problem in completing my work:

ValueError: cannot index with vector containing NA / NaN values

Below is the code I ran:

DF[DF.col.str.contains("foo")]
DF[DF.col.notnull()][DF.col.dropna().str.contains("foo")]

What’s causing it, and how can it be resolved in the “Cannot mask with non-boolean array containing NA / NaN values“ in the python?

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2 Answers

  1. Best Answer
    Expert

    The cause:

    I have a flag for that:

    In [11]: df = pd.DataFrame([["foo1"], ["foo2"], ["bar"], [np.nan]], columns=['a'])

In [12]: df.a.str.contains("foo")
Out[12]:
0 True
1 True
2 False
3 NaN
Name: a, dtype: object

In [13]: df.a.str.contains("foo", na=False)
Out[13]:
0 True
1 True
2 False
3 False
Name: a, dtype: bool

    From the above program, you can see that the data in your program are not strings, they are NA or NaN. However str.contains has a requirement that it must be a string, cannot numbers or mix with numbers. This is the reason of your error.

    Solution:

    To fix this error, let’s do as my following suggestion:

    In [21]: df.loc[df.a.str.contains("foo", na=False)]
Out[21]:
a
0 foo1
1 foo2

    Another way for this error is:

    df[df['Product ID'].str.contains("foo") == True]

    Or

    df[df.col.str.contains("foo").fillna(False)]
    If you follow these above suggestions, your error will be solved effectively. Good lucks!
    • 0

  2. You can use the following for columns that do not contain a single word: 

    df[df['Product ID'].str.contains("foo") == True]

    We hope you find this helpful.

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