Time-date chart plotting

[Midjack]

How can I create a time-date graph such that the values are plotted at the
correct time positions within the date range rather than all on the date
vertical axis?

N N
N N
N N
N N THIS
N N
N N
Jan 1 Jan 2

Rather than
N N
N N
N N NOT THIS
N N
N N
N N
Jan 1 Jan 2

 

[Del Cotter]

How can I create a time-date graph such that the values are plotted at the
correct time positions within the date range rather than all on the date
vertical axis?

Choose Chart type XY (Scatter) instead of Line. Line has only the
options of Category (which won't distribute the values properly) and
Time-scale (which, for some bizarre reason, Microsoft limits to whole
days only - no times available).

Time-scale can sometimes be useful as a sort of Interval scale for Line
and Area chart types, but because it only does integers, not fractions,
it's no good to you here. Only a proper interval/interval chart type
will do.

Also, make sure the X values are proper "date plus time" format all in
one cell. A date in one cell and a time in another won't work.

 

[Midjack]

Many thanks Del. That seems to work fine after a little tinkering with both
of the axes.

 

[Jon Peltier]

Choose Chart type XY (Scatter) instead of Line. Line has only the options
of Category (which won't distribute the values properly) and Time-scale
(which, for some bizarre reason, Microsoft limits to whole days only - no
times available).

Del -

It's still a category axis. I think the magic done under the covers simply
skips some categories in between to plot uneven intervals of whole numbers.
So we're still stuck with days only.

What you could do if you like the way the date axis is formatted (I know I
do), is to make a line chart with a hidden series (no markers or lines) to
control the axis, then add your real data as XY series, using real dates and
times for the X values. These somehow are allowed to display in between
categories and show times other than midnight on the days along the axis.
This combination Line-XY approach also helps to display data where the
series don't have points on the same days. Line chart series are tied to the
dates for the first series, but XY series are independent of each other.

- Jon

 

[David]

Jon,
This is just what I need. I've had a go, but am failing miserably so far.
I've been looking at your pages for an example but no joy so far. If there is
a specific example on your site could you please point me at it.
Thanks

 

[Jon Peltier]

Too bad you deleted the post you were replying to.

- Jon

 

[Del Cotter]

Too bad you deleted the post you were replying to.

Jon, this is the context:

 

[Jon Peltier]

I figured it was something like that. Too lazy to look it up.

Here's the protocol, which doesn't work in 2007 (doh! MS broke the
independence of the XY and line series in a combo chart with a date scale
axis).

Make a series with two points, like the min and max of your X axis
(date-time), and zero y values. Format the axis as you like it, and format
the series to be invisible (no line, no markers). Copy the XY data for the
XY series, select the chart, use Paste Special to add the data as a new
series. Right click this series, Chart Type, choose XY. Right click the
series (now XY), Format, and move it back to the primary axis. Repeat to add
more XY series if necessary.

I have an upcoming series for my blog which will deal with category axes,
but I need more time to make it pretty.

- Jon

 

[David]

Thanks for that Jon (and sorry about deleting post last time)
I am using Excel 2002
I followed your protocol and produced a chart but the xy data did not quite
line up with the category x axis like i was hoping.
Here's my numbers:
Line chart: (01/01/01, 0) (03/01/01, 0)
set xmin = 01/01/01, set xmax = 04/01/01
xy data: (01/01/01 05:00,1) (03/01/01 17:00, 4)
after copy, paste special, chart type = xy, format\axis\primary axis
I find that the 2nd xy data point is out of position in the 04/01/01
interval on the x category axis (rather than 17/24ths along the 03/01/01
interval as hoped for)
Is this in line with your expectation?
Thanks

 

[Jon Peltier]

You have to format the date scale axis so that the value (Y) axis does NOT
cross between dates. Otherwise the chart is still correct, but the ticks
occur at noon, not at midnight, so the XY points appear incorrect.

- Jon

 

[Jon Peltier]

I've illustrated this in today's blog posting:

Line-XY Combination Charts
http://peltiertech.com/WordPress/2008/06/26/line-xy-combination-charts/

- Jon

 

[David]

Thanks Jon,
I've read the blog and find it to be informative and well presented

 

[water]

You can try changing the axis to text format

 

[Jon Peltier]

Even better, use an XY chart. You need the full date and time values in
the cells containing the X values.

- Jon