Hey Adam
Well, There is a major problem with what the old charts used to plot
considering, log of a positive number smaller than 1 is supposed to be
negative.
Consider the following data, for example (I added g1 to g4) to your data:
data.addRow(["a", -1000]);
data.addRow(["b", -100]);
data.addRow(["c", -10]);
data.addRow(["d", -1]);
data.addRow(["e", -0.1]);
data.addRow(["f", 0]);
data.addRow(["g1", 0.0001]);
data.addRow(["g2", 0.001]);
data.addRow(["g3", 0.01]);
data.addRow(["g4", 0.1]);
data.addRow(["h", 1]);
data.addRow(["i", 10]);
data.addRow(["j", 100]);
data.addRow(["k", 1000]);
The columns g1 to g4 should be presented as negative, their log is a
negative number, by doing so the values should form a straight line.
It is true that in the old version it was implemented in a different way,
plotting 0.1 in a positive location and not plotting g1 - k on one straight
line, I find that simply inconsistent with what logarithmic scale is - a
plot of the log of values.
Badtnik
On Wed, Aug 11, 2010 at 12:33 PM, Adam <[email protected]> wrote:
> -1000,-100,-10,0,10,100,1000 should be equidistant ticks on the x-axis
> and should represent these values.
> What I'm referring to works fine on the old Google Visualization
> Charts (see my code below).
> However it doesn't work on the new corecharts.
>
> <html>
> <head>
> <script type="text/javascript" src="http://www.google.com/jsapi";></
> script>
> <script type="text/javascript">
> google.load("visualization", "1", {packages:["barchart"]});
> google.setOnLoadCallback(drawChart);
> function drawChart() {
> var data = new google.visualization.DataTable();
> data.addColumn('string', 'item');
> data.addColumn('number', 'sales');
> data.addRow(["a", -1000]);
> data.addRow(["b", -100]);
> data.addRow(["c", -10]);
> data.addRow(["d", -1]);
> data.addRow(["e", -0.5]);
> data.addRow(["f", 0]);
> data.addRow(["g", 0.5]);
> data.addRow(["h", 1]);
> data.addRow(["i", 10]);
> data.addRow(["j", 100]);
> data.addRow(["k", 1000]);
> var chart = new
> google.visualization.BarChart(document.getElementById('chart_div'));
> chart.draw(data, {width: 800, height: 300, logScale:true });
> }
> </script>
> </head>
> <body>
> <div id="chart_div"></div>
> </body>
> </html>
>
>
> On Aug 10, 6:46 pm, Badtnik <[email protected]> wrote:
> > Hi
> >
> > So you are suggesting the bars should not at all be affected by
> > logScale=true?
> > I mean, for what I understand, the purpose of logarithmic scale is indeed
> to
> > show a 'distorted' version of the data to help display very large value
> > alongside very small values. so 0.001 and 10000 can both have reasonably
> > sized bars representing them instead of the former being less then 1
> pixel
> > high.
> >
> > Can you sketch some example of how you would like to see a lograthmic
> scaled
> > chart of some example data ?
> > Badtnik
> >
> > On Tue, Aug 10, 2010 at 5:23 PM, Adam <[email protected]> wrote:
> > > Hi Badtnik
> >
> > > I will try to clarify what I meant.
> > > As an example, let's take a Column Chart with logScale=true.
> > > In this case the y-axis will be labeled in a logarithmic fashion
> > > (example 0, 10, 100, 1000 ...)
> > > However, the column values are not logarithmic - they are the real
> > > values. So for example, a column having a real value of 1000 will
> > > correspond to the 1000 y-axis label.
> >
> > > Since the data values are the real data values and not logarithms, I
> > > don't see any problem having the same method of logarithmic labeling
> > > of the negative y-axis.
> >
> > > On Aug 10, 12:55 pm, Badtnik <[email protected]> wrote:
> > > > Hey Adam
> >
> > > > What you are suggesting is interesting but might cause a lot of
> > > confusion,
> > > > for example:
> > > > - the values -10 and 1/10 will be positioned in the same height
> > > > - the value 0.5 will be positioned lower than -0.5
> > > > In general, the positioning function you are suggesting is not
> monotone
> > > nor
> > > > is it continuous.
> >
> > > > Wikipedia:http://en.wikipedia.org/wiki/Logarithmic_scaleseemsto only
> > > > describe logarithmic scale of positive values
> > > > Do you have any reference to literature or an example of a well known
> > > > charting tool that behaves that way?
> >
> > > > Badtnik
> >
> > > > On Mon, Aug 9, 2010 at 6:30 PM, Adam <[email protected]>
> wrote:
> > > > > Why does the logScale configuration option of the Column and Bar
> > > > > Charts require all values to be positive? (according the the
> > > > > documentation)
> >
> > > > > There is no reason for negative values not to have a log scale. The
> > > > > scale should be calculated according to the absolute values of the
> > > > > data. So the negative log scale would be something similar to -1,
> -10,
> > > > > -100, ...
> >
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