brendan wrote:I am having difficulty with your point about continuous v categorical data in line graphs. As i understand it, a classic line graph might be to plot something against time. That is, again as i understand it, continuous interval data and not categorical. Classic line graph shapes like exponential, sigmoid or standard deviation are also presumably based on continuous rather than categorical, otherwise the shape would be irrelevant.
Okay, I think I see the problem: Terminology! You are right about a classic line graph but that is not what OOo is doing in its version of a
line chart. The term line chart is a bit of a bastard term. What you are calling a classic line graph Calc calls an xy-graph Spreadsheet graphics are basiclly pretty crappy for several reasons and bad nomenclature is one of them.
Let's take the idea of graphing something say children's height against time where the child's height is measured in months but not every month—say the parents' forget some months so you have something making up some data heights measured at months = (12, 13, 17, 18 20, 21, 22, 30) and heights = (24, 25,30, 31, 33, 33.5, 34, 41). All data just made up on the spot. In the attached file I have plotted the data with months as continuous (xy-plot) in Figure 1a and categorical (line chart) in Figure 1b.
What OOo is doing when you use a line chart is treating the spaces between each value as being equal. So in the chart, the difference between 12 & 13 months equals the difference between 22 and 30 months.
Translated into your plot, in a line chart Calc would give the the difference between -280C and -20 and -20 and 19 the same spacing.
Currently in the graph you have posted it looks like you are actually using an xy-graph since the spacing does not appear to be the same. This might explain why there is no stacked line graph option. Unless you are somehow rigging the x-axis layout? I clearly was not paying enough attention to that plot earlier.
The same with my graph which charts temperature as the interval. I wish to stack the two data sets as the two individual data sets (heat transfer coefficients) sum to form the overall coefficient. But i cannot get a continuous line from either a stacked line or stacked area graph (but can on unstacked). I cant see the logic of it allowing continuous line for unstacked but not stacked so presume it must be a bug rather than an attribute of the type of graph.
I see what you mean. I don't know either and I am getting a different result -- I cannot get an acceptable line when there is missing data. I may have a problem with Calc.
What I don't understand is what the stacked graph is supposed to show. Are you trying to show HTC radiated + HTC conducted?
If so, it would probably be as good as anything to simply add another column to your data, add them together and graph a third line on the graph or, probably better, do a second graph. If I understand what you are doing, there are some problems in using something like a stacked or area type charts due to how how the human eye reads the difference of lines on some slopes and two graphs are likely to be better in many cases.
I may be wrong but I think that you can do everything you want fairly easily using xy-graphs which are your classical line graphs.
I hope this is of some help, or at least that I have managed to confuse you a bit more
