I was coninced that that rather than doing an order of
magnitude estimate of the confidence region it's better
to have the correct concave shapes that indicate the
95% confidence level for the regression line.
It also turned out that the previous expression was
missing a factor of 1/sqrt(n).
Signed-off-by: Robert C. Helling <helling@atdotde.de>
The goodness of fit of a regression line is the percentage
of the variance of the y values that is explained by the
dependence on the x values.
Set the alpha value of the regression line to this goodness
of fit.
Further, set the width of the regression line to a standard
deviation of the values from the regression line valies.
Signed-off-by: Robert C. Helling <helling@atdotde.de>
The old code didn't consider that labels can peak out of
horizontal axes if labels are under ticks.
This commit takes this into account. However, it must be
noted that this is only heuristics: Before setting the
size of the axes, the actual minimum and maximum label are
not known, because we round to "nice" numbers. But the
size of the axis can only be set after knowing the overhang,
leading to a circular dependency. Therefore, the code
currently simply uses the minimum and maximum value of
the data, hoping that the "nice" values will not format
to something significantly larger. We could do a multi-pass
scheme, but let's not for now.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
It turns out that the wrong base class was used for the chart.
QQuickWidget can only be used on desktop, not in a mobile UI.
Therefore, turn this into a QQuickItem and move the container
QQuickWidget into desktop-only code.
Currently, this code is insane: The chart is rendered onto a
QGraphicsScene (as it was before), which is then rendered into
a QImage, which is transformed into a QSGTexture, which is then
projected onto the device. This is performed on every mouse
move event, since these events in general change the position
of the info-box.
The plan is to slowly convert elements such as the info-box into
QQuickItems. Browsing the QtQuick documentation, this will
not be much fun.
Also note that the rendering currently tears, flickers and has
antialiasing artifacts, most likely owing to integer (QImage)
to floating point (QGraphicsScene, QQuickItem) conversion
problems. The data flow is
QGraphicsScene (float) -> QImage (int) -> QQuickItem (float).
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
The coordinates of these were calculated when creating the feature.
This is wrong, because the min/max values of the axes can change
on resize to get "nice" number. Therefore, recalculate after resizing.
This means that the general "LineMarker" class has to be split into
two classes, one for regression lines and one for median/mean
markers.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
Easy enough to implement, but one weirdness:
To get the height of the rotated text, one has to access the
width() member of the boundingRect. I'm not sure if that makes
sense, but so be it.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
Replace by custom implementation, with the ultimate goal to
remove the QtCharts module. This doesn't yet display axis
titles or a grid.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Since we want to get rid of QtCharts, we have to render our own
title. Simply keep around a QGraphicsSimpleTextItem and put in
the center of the chart. Define the borders to the scene as
constants.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
The chart was passed as argument to the function recalculating
the axis labels. Instead, pass the chart in the constructor of
the axes and save it. This gains us flexibility for the future:
There will be more functions that need to access the chart (e.g.
resizing of the axes).
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
We don't really give a user visible error message which is kind of a problem,
but at least we don't crash anymore.
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
A steep regression line would shoot out of the chart. Therefore,
clip to the y = minY and y = maxY lines.
QtGraphicsScene has its own clipping routines, but they are
very general, so let's do this trivial case by hand.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
For better visual guidance, format labels as "count (percentage)"
in horizontal bar charts. In vertical bar charts two lines are used
anyway.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
The old ways was to select the chart first, then depending on
the chart choose the binning.
Willem says that it should work the other way round: select
the binning (or operation) and make the charts depend on
that.
I'm not arguing one way or the other, just note that the new
way is much more tricky, because it is easy to get unsupported
combinations. For example, there is no chart where the
first variable is unbinned, but the second axis is binned
or has an operation. This makes things distinctly more tricky
and this code still needs a thorough audit.
Since this is all more tricky, implement a "invalid" chart
state. Ideally that should be never shown to the user, but
let's try to be defensive.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
The StatsView shows the chart described by the StatsState structure.
It is based on a QML ChartView. This should make it possible to
easily port to mobile. It does not include any of the UI around
the chart, viz. the variable and chart selection, etc.
The code checking for the statistical significance of the regression
line was written by Willem.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
Signed-off-by: willemferguson <willemferguson@zoology.up.ac.za>
