General
Purpose of feature: analysis of the metrics of tracked plots from current and historic tracks. Plotting is independent on event registration (sailing, weather and sea conditions). Therefore feeding data to the Barchart requires no special effort from your side, except doing some tracking.
Local TOC
Openers and content (top)
The Barchart subpage - or just 'Barchart' - opens from:
- a) Action on current track menu
- b) Action on historic track menu
- c) Action on historic tracks or track sections menu
The back button in the teal blue navigation bar displays as:
- a)
- b)
- c)
(Provided The Hide default Tzone number switch is ON and default Tzone applies - else a suffix appears, e.g. )
Its content is based on:
- Tzone selected
- what is being / has been tracked
- time range:
- a) and b) Departure time -> Arrival time (so far) for given track
- c) set by The Datepickers
- setting of:
Like the Piechart subpage, the chart is static, i.e. it doesn't change even when opened from a).
The Barchart - as well as the Piechart - is based on the Charts library licensed under Apache License 2.0 - Copyright 2015 Daniel Cohen Gindi & Philipp Jahoda.
The duet picker panel (top)
is placed at the top and consists of two independent wheels:
The Metric picker to the left selects what to show:
- Distance
- Average speed
- Max speed
The Granularity picker to the right selects how to show:
- 1 bar
- 2 bars
- 4 bars
- 8 bars
- 16 bars
- 32 bars
- 64 bars
- 128 bars
Values are shown with varying number of decimals - depending on value sizes.
Calculation rules (top)
The time range specified with The datepickers is used to fetch plots (aka locations) falling within that range, measured by seconds.
When opening from the Action on historic tracks or track sections menu, set Date+clock mode for precise specification - Barchart calculations and display of time are based on seconds.
Effective time range display (top)
'Empty time' from Time from to first plot found, as well as 'empty time' from last plot found to Time till is cropped to produce an effective time range:
...........datepickers........
...Plots.... ...Plots.... ...Plots.... ...Plots....
...effective time range....
The combined screenshot below shows how the effective time range is displayed at the bottom of the Barchart, as well as indication of units selected with Measurement picker.
Time-slice (top)
The chart consists of a number of bars, each representing a same-length time-slice. So if the effective time range covers 3600 seconds and a 4-bar granularity was chosen, then each bar represents 900 seconds.
Selecting a bar by tapping it, highlights it and displays its time-slice, replacing the effective time range display:
At the same time, a button is enabled in the teal blue navigation bar:
A tap at the bottom of the chart un-selects the bar and revokes the effective time range display. This can also be achieved by tapping the selected bar again.
Multiple tracks (top)
The Barchart may cover plots from a tiny part of a single track, a whole track, parts of more tracks as well as all tracks (the whole history). Time between single tracks will / may be represented as empty bars - depending on granularity and time range:
Empty bars are represented by zero (or zeroes) and thus invisible as bars, but tapping a zero still selects a bar and displays its time-slice; above the sixth bar (below the black arrow) was tapped (the button is replaced by a dim text below the red arrow).
A dim text may also appear.
The first and the last bar can never be empty because of cropping.
Examples (top)
Below a series of screenshots of charts follow. All are based on plots from tracking during the summer season 2018.
Example 1: Distance, 8 bars (top)
Values for effective time range and time-slices are presented in the units selected with Measurement picker.
Example 2: Distance, 16 bars (top)
The granularity scale doubles for each step - therefore the distance value for a bar is split into two bars when increased one step, and the time-slice halved. For example: values 207 and 79 (in bar 5 and 6) is a split of value 286 (in bar 3 in previous example).
Applied to a limited time range - e.g. for a day cruise - high granularity may give a good picture of speed and progress.
Example 3: Distance, 128 bars (top)
The individual bar values are not shown with this high granularity - not even on an iPad in Landscape format! However, with a precise hand, bar selection is still feasible - above, the very last bar is selected (whereby the button is enabled).
Example 4: Average speed, 8 bars (top)
No activity in the second to last bar - just like in Example 1: Distance, 8 bars. Which btw has exactly the same profile: average speed is a simple calculation of distance (example 1) divided by time-slice size (which is the same for all bars).
The not very impressive avs values are caused by inactivity most of the time.
Example 5: Max speed, 8 bars (top)
An okay value in the second bar (5.84 kn), though the average speed was not so good (.022 kn)!
Example 6: Map opened from Barchart (top)
Metrics for a one-day trip is shown, and the tallest column is selected:
A tap on opens:
(The Show Boat & MaxSpeed pin switch was set ON after a tap on the button).
Sailor Logbook S App manual - © Copyright 2018 CoaSoft ApS Denmark