Limitations

What chart support does not do, and why. Most of these are deliberate stopping points rather than oversights, and each says what to do instead.

Chart kinds with no template

A created chart starts from a chart part Excel itself wrote, kept verbatim in the package, so the result is what Excel would have produced. That means a kind with no template cannot be created at all, rather than being approximated:

• percent-stacked bar and column
• 3-D charts of any kind
• stock, surface and of-pie charts
• combo charts — a plot area with more than one group
• region maps (the cx: filled map), whose geography Excel resolves online

All of these are read normally, including their series and formatting and, for the c: kinds, their cached data. The restriction is on creating them.

A combo chart is also the one case addSeries cannot extend, since there is no single group to add the series to.

Style and colour parts are not read

Excel keeps much of a chart's appearance in two parts beside the chart itself, style1.xml and colors1.xml. Neither is read into the formatting cascade, so a property written at no rung of the chart XML resolves to nothing — meaning "Excel takes this from the style", not "this is off".

For a c: chart that is a modest gap: most of what you see is written in the chart part. For a cx: chart it is a large one, because the cx: schema keeps almost all appearance in the style part. Reading and writing a cx: chart's data and structure works; formatting one from code reaches much less than the equivalent c: call would.

The parts are preserved on write, so nothing is lost by the package not reading them. FormatSite's level already admits :style, so adding the rung later would extend the cascade rather than change it.

chartEx charts carry no cached values

Excel writes no value cache into a cx: chart part, so getChartData throws for a ChartEx and a chart created with addChartEx shows nothing until Excel opens the file and computes it. Read the source cells instead, through getChartRanges and XLSX.getdata.

Errors in cached data

Excel caches #N/A as itself and every other error value as 0, so a #DIV/0! in the source is indistinguishable from a genuine zero once the file is written. This is a property of the format, not of the package. Where the distinction matters, read the source cells — see Blanks and errors.

Values are the ones Excel last wrote

Nothing is recomputed. A chart's cached values are those of the last save by Excel, and a series added by addSeries caches the cells as they stand at that moment. Changing a cell afterwards does not update any chart that plots it; Excel does that when it next opens the file.

The same goes for formulas. A cell written by XLSX.setFormula has no value until Excel calculates it, so a series plotting it is cached with no values, and getChartData finds none. Excel recalculates on opening and draws the chart from the results, so the chart looks right there. To read the values in Julia, compute them there too, or read them back from a file Excel has saved.

Legend entries follow series order

Excel draws a legend entry for each series, in series order, and can hide entries but not reorder them. So setLegendEntryDeleted hides entries, and there is no setter for their order. To show a legend in another order, add series that plot zeros, in the order wanted and formatted to match, and hide the entries of the series that draw the data; A Likert chart shows how.

Lines and dashes: symbols in, strings out

Dash, cap, compound and join are set with symbols (:sysDot, :rnd) and read back as strings ("sysDot", "rnd"), because a getter reports what the file holds. An Excel name you set comes back as its DrawingML equivalent.

Markers belong to some chart kinds only

A marker is a property of a line, scatter or radar series. Setting one on a bar or pie series throws, because the schema gives c:barSer no c:marker child. The same applies to the options addSeries takes: smooth is for line and scatter series, line for scatter, and color has no meaning on a pie or doughnut chart, whose points are coloured individually.

Resolving text properties

getLabelTextProp resolves one run property up the cascade for a series' data labels. There is no equivalent for a chart title, an axis title or the legend — only the plural …TextProps getters, which report what one element says. Setting is symmetrical; the gap is on the reading side.