Charting scientific data - Excel 2003

[Alex]

Every once in a while I need to plot some spectral data. Because it's not
very often and it's just simple plots, I can't justify to my boss the
purchase of fancy and expensive plotting software programs (SigmaPlot,
Origin, etc.). However, I can't figure out how to one thing in Excel:

I have data with x being time and y being some value. Also, there are many
points with y=0. I want to plot an xy scatter graph with a smoothed line
connecting the points. However, because most points are at y=0, most of the
plot is hidden by the x axis. Problem is solved if I set the y minimum at,
say, -2 but then the axis numbering starts at -2 instead of 0. How can I set
the minimum at -2 but have the numbering begin at 0?

 

[Bernard Liengme]

I am not sure I totally understand the problem but here is a suggestion
Suppose the data looks like the first two columns here
x y y'
1 0 2
2 3 5
In the third column I have the formula =b2+2
Then I select all the a column; hold down CTRL, select all the C column, and
make the chart from these two columns
best wishes

 

[PBezucha]

Some ideas:

There is nothing simpler than using connecting line thicker then the border
lines of plot area; you can distinct also by means of different colors. There
can be problems with connecting line disappearing under zero borders, if you
select continuous line mode, but this phenomenon somehow distorts the overall
image anymore.

If label -2 in your proposal is offending you, you can deck it with an empty
(white) textbox.

Visualization of spectra serves usually only for obtaining a rough overview;
absolute values don’t matter. So you can omit y-scale labeling at all. The
baseline at y=0 will be either self marked by plenty of zero values, as you
unwittingly notice, or you can draw a new y=0 line and mark it by a textbox
'0'.

 

[Alex]

Thank you for the reply. It's not necessarily the -2 that's offending me,
it's the fact that the scale starts *counting* at -2. So we have something
that goes -2, 3, 8, 13... etc instead of 0, 5, 10, 15. Yes, I could have it
start at -5, but that gap is much large to look "nice". I was hoping that
there was a way (VBA?) to have excel start counting at 0. Guess not. No
worries, like you write, it's not really a big deal.

Alex

 

[PBezucha]

Alex,

If you have brought out such a neat example… you can even cut such a gap.
Scale y-axis between -1 and 15 with major unit 1, and deck "offending" labels
-1, 2..4, … with patches (rectangles from Drawing). The only thing you could
now miss are horizontal gridlines. Anyway, many technical journals recommend
avoiding them, and the zero (and possible some other) line can be resolved
with a drawn line as I have written. All these operations has to be done
manually, and you cannot change any chart element.

Certainly Excel is not much scientific (except for human sciences) language,
though its potential is sometimes a surprise.

 

[Jon Peltier]

Format the axis not to show axis ticks and tick labels.

Add an XY series to produce pseudo-axis features:

Arbitrary Axis Scale
http://peltiertech.com/Excel/Charts/ArbitraryAxis.html

- Jon