topic log scale and bar-offset in bar chart in QlikView

log scale and bar-offset in bar chart

amien — Mon, 13 Jun 2011 17:01:13 GMT

i have created a bar chart that is also known as the bridge chart or waterfall chart.

some steps in the bridge are negative values, some are positive.

the bridge goes from actual to forcast. the steps of the bridge are certain segmemts.

I use the bar-offset settings to make my bridge . .works perfectly.

the y-axis goes from 0 till 150. i dont want the y-axis to start at 0 because otherwise the steps look very small..

therefore i checked 'Log Scale' .. now the chart starts at 108 .. perfect!

only problem is that some steps in the bridge are negative. Checking 'Log Scale' will have the effect that those steps are gone.

How can i use the Log scale option, but still show the negative values in the chart?

log scale and bar-offset in bar chart

johnw — Mon, 13 Jun 2011 20:11:53 GMT

Can you post an example?

My guess is that it's a bug, or as QlikTech might reply, working as designed (but the design is poor and should be improved).

Normally, you couldn't have positive and negative values on the same log scale chart. The reason is that the distance from the positive values to the negative values is infinite. So I'm guessing that QlikView was coded to simply exclude the negatives as a way of avoiding that problem.

But with a waterfall chart, as long as all the values remain above the 0 axis, there's no fundamental reason you couldn't display the negatives. I suspect QlikView's code is merely not sophisticated enough to recogize the difference between having data at or below the axis and simply having negative data in a waterfall chart that remains above the axis.

log scale and bar-offset in bar chart

amien — Tue, 14 Jun 2011 14:49:39 GMT

i unchecked force 0 and for some reason it worked

log scale and bar-offset in bar chart

johnw — Tue, 14 Jun 2011 16:20:30 GMT

Hah! I didn't even think of that. On a logarithmic chart, 0 is also infinitely far away from any positive value. So I guess QlikView is smarter than I thought with the handling of negatives, and it was the forced zero causing the problem. Anyway, good job figuring it out. I'm glad I was wrong about the cause of the problem.

log scale and bar-offset in bar chart

amien — Wed, 15 Jun 2011 09:24:34 GMT

Thanks for your reply btw ..

i dont full understand the logic about this issue, but it works and that whats count at this moment