How large is a chart?

  • Thread starter Thread starter Guest
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G

Guest

I am just asking out of curiosity. How large, in kilobytes, is a chart; say,
a 1000-point x-y scatter? I had a large file whose size was halved when the
charts were deleted (actually, they were lost, along with formats and
scenarios, when the file got corrupted; see "story" below).

In my non-expert view, it should not be so large, because the only
information unique to the chart is its position, size, format, and similar
details. The actual data itself is contained in the data-range cells, so
should not have to be repeated in the chart itself. Not only the formulas
but their values, too, are stored in the cells (note the option in manual
calculation mode to calculate cells before saving, which is presumably always
done in the automatic mode). This being the case, what is the bulk of a
chart's memory size?

http://www.microsoft.com/office/com...ebab74-7522-4aa9-8c9f-cdab69104db7&sloc=en-us
 
You could answer this yourself. I created a workbook with one sheet, put X
and Y into A1 and B1, filled A2:B1001 (1000 rows) with =RAND(). The file was
99840 bytes. I added a default XY chart with 10 points, the file went to
104960 points. In fact, for different numbers of points in the series, the
file size varied as follows:

10 pts 104960 bytes
100 pts 108544 bytes
500 pts 122880 bytes
1000 pts 141312 bytes

the trendline formula for this data is:

y = 36.569636x + 104704.721480
R² = 0.999928

so 36.5 bytes per data point, and the blank chart was worth about 4865 bytes
(extrapolating to zero points and subtracting the size of the file with data
only).

When you start applying non-default formatting, the chart grows in size.
Adding chart and axis titles, changing plot area and legend formats, and
stretching the plot area and moving other chart elements around increased
the file with a ten-point chart to 105472 bytes. Changing the series formats
(marker color and shape, line style) had no effect, adding default data
labels had no effect. Adding data labels linked to the worksheet (Rob
Bovey's Chart Labeler, http://appspro.com) boosted the file to 110080 bytes.

Then things got funny. I deleted the data labels, and the file shrunk only
to 108544. I reapplied the default XY chart formatting and it shrunk to
107520. I deleted the chart, and the file became 103424 bytes, a gain of ~
3.5 k from the original data only file. So apparently there's some junk left
in the file when a chart has been created and formatted. This residual stuff
must be what leads to occasional worksheet, chart, and workbook corruption.

- Jon
 
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