CODEWITHSUNDEEP
pythonpandasnumpydataframe
Alexsander Santos
Alexsander Santos

Reputation: 117

Compare boolean Series

I need some help.

I have a dataframe with a int column. I want to test this values.

test1 = (data['CC'].shift(1) > 50) & (data['CC'] < 50)
test2 = (data['CC'].shift(1) < -50) & (data['CC'] > -50)

This code works and return a Series of 2000 rows. I have no problem with this.

0    False
1    False
2    False
3    False
4    False
Name: CCI, dtype: bool

I want to use this Series to add a new column.

if(test1):
    data['Sloop'] = '+S'
elif(test2):
    data['Sloop'] = '-S'
else:
    data['Sloop'] = 'N'

The if statement is not working:

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

Of course, the test1 and test2 exists here. The real code is:

if((data['CC'].shift(1) > 50) & (data['CC'] < 50)):
    data['Sloop'] = '+S'
elif((data['CC'].shift(1) < -50) & (data['CC'] > -50)):
    data['Sloop'] = '-S'
else:
    data['Sloop'] = 'N'

Same error. Please, some help.

Thanks

Upvotes: 1

Views: 57

Answers (1)

jezrael
jezrael

Reputation: 863751

Use numpy.select:

test1 = (data['CC'].shift(1) > 50) & (data['CC'] < 50)
test2 = (data['CC'].shift(1) < -50) & (data['CC'] > -50)

data['Sloop'] = np.select([test1, test2], ['+S','-S'], default='N')

Upvotes: 1

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