Database Reference
In-Depth Information
Figure 4-2. Creating a ratio with a Calculated Field
Now that we've created the ratios, how can we best visualize them? Let's start with a simple
bar chart of the aggregate ratios of each of the boroughs. To create one, we'll drag the
Bor-
ough
field from the Dimensions area on the left to the Rows shelf, and we'll drag the
Re-
cycle to Refuse Ratio
calculated field to the Columns shelf. Color wouldn't strictly be
needed, but we'll add it anyway for aesthetics by dragging
Borough
to the Color shelf.
Lastly, we'll sort the bars in descending order to put the borough with the highest recycle ra-
tio at the top. The screen shot in
Figure 4-3
shows the resulting view.
We can easily see from this simple bar chart that Manhattan has the highest ratio of recycle
to refuse, but that it still only recycles about one ton of material for every four tons of trash.
The ratio for Manhattan is about twice as great as the ratio for the Bronx.
Does this mean each community district in Manhattan had a higher recycle ratio than each
community district in the Bronx? Not necessarily, as we're dealing with the terms in the ag-
gregate.
How would we communicate the results at a community district level? If we just replace
Borough
with
CommunityDistrict
in the Rows shelf, then we'll get a bar chart where all the
