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Piper Ramirez
Piper Ramirez

Reputation: 413

If, And Statement not outputting accurate results in Python

df.loc[(df['Platform'] == 'A321') and (df['Days'] <= 14), 'Mods Applicable'] = 'CFM56 9th Stage Duct'

I'm trying to have the output of Platforms for A321 and Days less than or equal to 14 to print out the following 'Mods Applicable' but it's not ouputting that Platforms AND the Days.

Output results:

Output results

IF & Output:

IF & Output

Upvotes: 2

Views: 97

Answers (2)

Amir
Amir

Reputation: 1905

This is because comparing a Series to a value also returns a Series. Which means that the results of (df['Platform'] == 'A321') and (df['Days'] <= 14) are Series of true/false values and it doesn't resolve to a single true or false by default. So you can't and it!

You can replace the and with &. So it would become:

df.loc[(df['Platform'] == 'A321') & (df['Days'] <= 14), 'Mods Applicable'] = 'CFM56 9th Stage Duct'

Upvotes: 0

Nathaniel
Nathaniel

Reputation: 3290

Try using "&" instead of "and":

df = pd.DataFrame({'Platform': ['A123', 'A321', 'A321', 'B123'],
                   'Days': [10, 13, 20, 5]})

df.loc[(df['Platform'] == 'A321') & (df['Days'] <= 14), 'Mods Applicable'] = 'CFM56 9th Stage Duct'

print(df)

      Platform  Days       Mods Applicable
    0     A123    10                   NaN
    1     A321    13  CFM56 9th Stage Duct
    2     A321    20                   NaN
    3     B123     5                   NaN

I can reproduce the same error by using "and" instead of "&":

Traceback (most recent call last):

  File "<ipython-input-128-7957a219684b>", line 1, in <module>
    df.loc[(df['Platform'] == 'A321') and (df['Days'] <= 14), 'Mods Applicable'] = 'CFM56 9th Stage Duct'

  File "/Users/nathanielgates/anaconda3/lib/python3.6/site-packages/pandas/core/generic.py", line 1479, in __nonzero__
    .format(self.__class__.__name__))

ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

Upvotes: 1

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