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Relational Operators with Pandas Series

Relational Operators with Pandas Series

Let's find out why the puzzle gives a ValueError and how we can fix it.

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Try it yourself

Try executing the code below to see the result.

Python 3.5
import pandas as pd
def relu(n):
  if n < 0:
    return 0
  return n
    
arr = pd.Series([-1, 0, 1])
print(relu(arr))

Explanation

The problematic line is if n < 0:. Here n is the result of arr < 0, which is a pandas.Series.

In [1]: import pandas as pd
In [2]: arr = pd.Series([-1, 0, 1])
In [3]: arr < 0
Out[3]:
0 True
1 False
2 False
dtype: bool

Once arr < 0 is computed, we use it in an if statement because of how Boolean values work in Python. Every Python object, not just True and False, has a Boolean value.

We can test the truth value of a Python object using the built-in bool function. In Python, everything is True except the following:

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