Before we dive into the process of data cleaning, which might be very time-consuming, it is always useful to define the scope of work—which columns and rows we actually need to clean. For this chapter, let's restrict the scope to the lowest level of the hierarchy—specific battles (level=100—pages for events with no children). We can use the equality operator to generate a Boolean mask, and then use this mask to filter the dataset:
>>> battles = data[data.level == 100] >>> battles.shape(147, 23)
There are many columns in the dataset—enough for pandas to omit the middle part when printing. As we'll be mostly focused on time, geolocation, names, and casualties of each side, let's define those columns of ...
