plotting line charts with formula based 'gaps'

[mick perry]

I am trying to visually represent different conditions on a line chart (e.g.
underlying data is rainfall in the UK; plot as a dashed line. The conditions
are times when the wind is from the north, times when the temperature is
below 10C, and both; plot as different thickness lines on top of the
underlying). I've been doing this by calculating when the different
conditions are true in diff't columns, returning the underlying data when
they are and returning N/As when they're not, then cutting and pasting as
values, sorting to delete the N/A's, sorting back by date and displaying as
several lines of different formats on top of each other on the chart. Any
other ways to do this? if I could leave gaps in lines when the formula value
is N/A it would make this much faster, but i can't get it to stop
interpolating unless i clear the cells...

 

[Bernard Liengme]

Have your tried enter =NA() in the blank cells? This displays as #N/A which
the chart engine ignores.
Also there is a chart option to specify that blanks are to be ignored and
points are to be joined.
In XL2003; click chart; open Tools | Options | Chart and locate area
specifying how blanks are to be treated
In XL2007: Chart Tools Design; Data group; Select Data tool -- at bottom of
dialog box "Hidden and Empty Cells"
best wishes

 

[Jon Peltier]

Bernard -

Don't forget that the "Empty Cells" setting applies only to empty cells,
not cells containing "" or #N/A.

- Jon

 

[Bernard Liengme]

Agreed but the OP seems to have really empty cells (missing data)
But I should have added the formula proviso for the sake of others
Cheers

 

[mick perry]

thanks for the prompt responses - unfortunately I have formulas in the empty
cells so the "Hidden and Empty Cells" instruction still interpolates between
the values (for my chart to work I need to leave gaps in the lines on the
charts, so that you can see which sections of the underlying data fit the
conditions and which ones don't)

 

[Bernard Liengme]

Can you change the formula to enter NA() when the plotting data is not
available
Show us the formula so we may help you better
best wishes

 

[mick perry]

As an example, if in column A rows 1-10 i have the values 1, 2...10 etc. In
cell B1 I have a formula =IF(AND(A1>2,A1<6),A1,NA()) which is then duplicated
down to B10. In C1 I have the formula =IF(AND(A1>6,A1<10),A1,NA()).

I want to plot column A as a line chart (dashed for example), and then I
want to plot columns B and C as line charts on top of it in different
colours, line styles etc to highlight different conditions on the curve.
This works fine.

The problem is that if the formula in columns B and C are more complicated
and select non-contiguous sections of column A then the lines are
interpolated. So for instance if the formula in col B is
=IF(OR(AND(C17>2,C17<6),AND(C17>6,C17<10)),C17,NA()) then excel draws one
line from 3 to 9, rather than two lines going from 3-5 and 7-9. The only way
i can stop it interpolating between the two sections is to delete the
folrmula, but this isn't practical in spreadsheets with thousands of rows and
many columns of conditions. So - I'm looking for a way to leave formulas in
all the cells but not have excel join up the lines where there isn't any
data. Please let me know if this doesn't make sense. Thanks...

 

[Bernard Liengme]

The NA() part of the formulas cause the chart engine to ignore the cell and
joint adjacent points.
If you rewrite the formulas in the form =IF(AND(A1>2,A1<6),A1,"") you will
get gaps when the cell displays a blank
best wishes

 

[mick perry]

thanks - but unfortunately using "" instead of NA() as in

=IF(OR(AND(C16>2,C16<6),AND(C16>6,C16<10)),C16,"")

causes zero values to be displayed on the chart instead of gaps (even when
the 'Show Empty Cells' button in 'Hidden & Empty Cells' has been set to
'Gaps')

 

[Bernard Liengme]

Would you like to send me a sample file
Please get my email address from my website

 

[Andy Pope]

Hi,

The use of NA() only removes the data markers it will not cause a break
in the line. The line will be interpolated between any data points that
have a numeric value.

You can see the variations here.
http://www.andypope.info/charts/brokenlines.htm

Cheers
Andy

 

[Jon Peltier]

That still won't provide a gap...

- Jon