Custom Charts – RallyDataJunkie Stage Table, Part 1

Over the last few evenings, I’ve been tinkering a bit more with my stage table report for displaying stage split times, using the Dakar Rally 2019 timing data as a motivator for it; this is a useful data set to try the table out with not because the Dakar stages are long, with multiple waypoints (that is, splits) along each stage.

There are still a few columns I want to add to the table, but for now, here’s a summary of how to start reading the table.

Here’s stage 3, rebased on Sebastien Loeb; the table is ordered according to stage rank:

The first part of the chart has the Road Position (that is, stage start order) using a scaled palette so that out of start order drivers in the ranking are highlighted. The name of the Crew and vehicle Brand follow, and a small inline step chart that shows the evolution of the Waypoint Rank of each crew (that is, their rank in terms of stage time to that point, at each waypoint). The upper grey bar shows podium ranks 1 to 3, the lower grey line is tenth. If a waypoint returns an NA time, we get a break in the line.

Much of the rest of the chart relies on “rebased” times. So what do I mean by “rebased”?

One of the things the original data gives us the stage time it took each driver to get to each way point.

For example, it took Loeb 18 minutes dead to get to waypoint 1, and Peterhansel 17m 58. Rebasing this relative to Loeb suggests Loeb lost 2s to Perterhansel on that split. On the other hand, Coronel took 22:50, so Loeb gained 290s.

Rebasing times relative to a particular driver finds the time difference (delta) between that driver and all the other drivers at that timing point. The rebased times show for each driver other than the target driver are thus the deltas between their times and the time recorded for the target driver. The rebased time display was developed to be primarily useful to the driver with reference to who the rebased times are calculated.

So what’s going on in the other columns? Let’s rebase relative to Loeb.

Here’s what it looks like, again;

The left hand  middle of the table/chart shows time taking in making progress between waypoints.

To start with we have the Stage Gap of each driver relative to Loeb. This is intended to be read from the target driver’s perspective, so where a driver made time over the target driver, we colour it red to show our target lost time relative to that driver. If a driver was slower than the target driver (the target made up time), we colour it green.

The Stage Gap is incremental, based on differences between drivers of based on the total time in stage at each waypoint. In the above case, Loeb was losing out slightly to the first two drivers at the first couple of waypoint, but was ahead of the third place driver. Then something went bad and a larget amount of time was lost.

But how much time? That what the inline bar chart cells show: the time gained / dropped going from one waypoint to the next. The D0_ times capture differences in the time taken going from one split/waypoint to the next. The horizontal bar chart x-axis limits are set on a per column basis, so you need to look at the numbers get a size of how much time gained/lost they represent. The numbers are time deltas in seconds. I ummed and ahhed about the sign of these. At the moment, a positive time means the target (Loeb) was that much time slower (extra, plus) than the driver indicated by the row.

Finally, the Pos column is rank position at the end of the stage.

If we look down the table, around Loeb, we see how Loeb’s times compare to the drivers who finished just ahead —and behind— hi. For drivers ahead in the ranking, their Stage Gap will end up red at the end of the stage, for drivers behind, it’ll be green (look closely!)

Scanning the D0_ bars within a column, it’s obvious which bits of the stage Loeb made, and dropped, time.

The right hand side of the figure considers the stage evolution as a whole.

The Gap to Leader column shows how much time each driver was behind the stage leader at each waypoint (that is, at each waypoint, rank the drivers to see who was quickest getting to that point).

Along with the Waypoint Rank, the Road Position and Gap to Leader, this is the only aspect of the table that is relative to the driver associated with that row: it helps our target (Loeb) put each other driver’s performance on the stage in the context of the overall stage rankings. The dot marker indicates the gap to leader at the end of the stage.

The 0N_ columns show the time delta on stage between each driver and Loeb, which is the say, the delta between the accumulated stage time for each driver at each waypoint. The final column records the amount of time, in seconds, gained or lost by Loeb relative to each driver in the final stage ranking (penalties excepted).

Looking at the table aound Loeb we see the column entries are empty except for the Gap to Leader evolution.

The original version of this chart, which I was working up around WRC 2018, also includes a couple more columns relating to overall rally position at the start and end of the stage. Adding those is part of my weekend playtime homework!

Author: Tony Hirst

I'm a lecturer at The Open University, with an interest in #opendata policy and practice, as well as general web tinkering...

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.