Major and minor gridlines on logarithmic axis excel 2007

[Vincent]

In excel 2007 all service packs.

Create a scatter plot with data greater than 1E13.
Select logarithmic axis with any base (such as 10)
Choose major and minor gridlines.

When the data is large (> 1e13) only major gridlines show up. Minor
gridlines only does work, but not major *and* minor.

Are their any solutions?

It's almost impossible to read a log plot without minor gridlines, and it's
important to highly the major lines as well with a dark line. Log plots are
essential in any engineering or scientific plotting.

Excel is slowly and painfully becoming quite standard for this type of
plotting.

 

[Bernard Liengme]

Please give as about six data points to try
best wishes

 

[Vincent]

use this data in two columns:
5 1.00E+13
12 2.00E+13
13 3.00E+13

Insert scatter plot.
Axis -> vertical axis with log scale
Gridlines -> horizontal -> major and minor

Try minor only and you see what it should look like.
Then change your y-axis data to 1E12, 2e12, and 3e12. the major and minor
suddenly show up.

for a log plot I typically make a dark black line for the 10's and light
gray for the 1's. It makes the log plot much more readable.

This has been broken for at least SP1 and SP2. It worked fine in 2003 and
before.

How do I make a bug report on this? I see no issues in the knowledge base
or usenet.

 

[Bernard Liengme]

Hi Vincent:
I can confirm your observation: with the data shown in your last message
Excel 2007 will not display minor gridlines while Excel 2003 can. I do not
think the data is very representative of most peoples work but I will report
the 'bug' to MS


Why not plot LOG(y) using =LOG(B2) etc
x y log(y)
5 1.00E+13 13
12 2.00E+13 13.30103
13 3.00E+13 13.47712125
Plot first and third column and now you can have minor gridlines

You could even plot all three columns; put log(y) on a secondary axis and
hide most of its effects other than the gridlines. Email me privately (get
my email from my website) and I can send you a sample file
best wishes

 

[B. R.Ramachandran]

Hi.

You can mimic minor gridlines indirectly by adding a second series to your
logarithmic plot.
Create two columns to contain the gridline information as shown below (Here
I am showing columns C and D and they start at Row 2.

Row C D
1
2 10 2e13
3 15 3e13
4 15 4e13
5 15 5e13
6 15 6e13
7 15 7e13
8 15 8e13
9 15 9e13

These are the gridline-information for the decade between 1e13 and 1e14. If
you want to show more decades, you could simply use the formula =D2*10 at D10
and fill down to as many decades as you want.
In Column C, I arbitrarily entered 10 in Row 2 (in scale on the x-axis) and
15 in the rest (slightly larger than the x-axis maximum in your logarithmic
plot).
Now add the series Column D (y-values) vs Column C (x-values) to your
logarithmic plot. Only the first data-point (10, 2e13) will show up (the
rest of the points are off scale); this is needed for doing the next step.
Include horizontal error bars to this series and format them as:
Display: Minus
End Style: No Cap
Error Amount: Percentage, 100.0%

Now change C2 to 15 so that that marker will also go off scale.

The error bars will mimic minor gridlines. Format their color, line
thickness, and line style as you wish to distinguish them from the major
gridlines.

With regards,
B. R. Ramachandran

 

[Vincent]

Bernard,
I appreciate your response and looking into this matter. I hope they will
eventually be able to create a hotfix for this bug.

I've seen a lot of confusion on usenet about the use of a log scale. A
typical reason you want to plot with a log scale is - 1) Increase the dynamic
range of the plot, and 2) look for exponential trends in you data (shows up
as linear).

It's not because you want to actually take the log of the data. Having a
log scale allows you to quickly read off the scale (mainly using the minor
gridlines). Taking the log of the data makes that very difficult.


This brings me to another annoyance with log plots on excel. Do not
continuously display pop-up errors when you plot zeros on a log plot. There
is nothing wrong with plotting this - just give me a graceful error only once
and plot blanks. Engineering data has zeros all the time, that should not
preclude visualizing it on a log scale!

 

[smmudge]

I have a somewhat related issue with Log axes graphs...

If I add error bars to data and display them with a linear y-axis, all is
well. If I convert the y-axis to log, some of the bars (not all) are not
finished correctly and Excel draws triangles to the next error bar.

Is there a work around for this?

Thanks. Steve

 

[Misange]

Lets say you have 100+/-120

in non logaritmic scale, you should have an error bar starting at -20
if you put that as a log, then you have an error because you cannot
calculate the log of a negative or null value. And thus excel is lost.
No solution than to change the data !

Misange migrateuse
http://www.excelabo.net


smmudge a écrit :