Performing Boolean selection
Indexes give us a very powerful and efficient means of looking up values in a Series based upon their labels. But what if you want to look up entries in a Series based upon the values?
To handle this scenario pandas provides us with Boolean selection. A Boolean selection applies a logical expression to the values of the Series and returns a new series of Boolean values representing the result of that expression upon each value. This result can then be used to extract only values where True was a result.
To demonstrate Boolean selection, let's start with the following Series and apply the greater than operator to determine values greater than or equal to 3:
This results in a Series with matching index labels and the result of the expression as applied to the value of each label. The dtype of the values is bool.
This series can then be used to select values from the original series. This selection is performed by passing the Boolean results to the [] operator of the...
