Initialise create.legend.labels so guideline = FALSE draws its legend

[sstoeckl]

chart.EfficientFrontierCompare() stops with

object 'create.legend.labels' not found

whenever guideline = FALSE and legend.labels is left at its default. Nothing
is drawn; the error comes from the legend block at the end.

create.legend.labels is built only inside the guideline block, and then used
unconditionally:

if(guideline){
  ...
  create.legend.labels <- paste("% Increase in Risk =", ...)
  create.legend.labels <- append(create.legend.labels, paste("% Increase in Return =", ...))
}
...
if(is.null(legend.labels)){
  legend.labels <- paste("min", match.col, "Portfolio")
  legend.labels <- append(legend.labels, create.legend.labels)
}

guideline defaults to TRUE only when match.col has two entries, so the
failing path is the ordinary one for a single frontier, and it is reachable with
two as well by passing guideline = FALSE.

The change

One line: create.legend.labels <- NULL before the guideline block, with a
comment saying why.

NULL rather than character(0) or a placeholder, because append() drops it.
That leaves one label per match.col, which is exactly the number of colours,
line types and widths the guideline = FALSE branch sets a few lines above, so
the legend stays consistent with the lines it describes.

Measured

Four edhec columns, match.col = c("StdDev", "ES"), labels captured by
tracing graphics::legend, so this is what the function passes rather than what
it looks like it should:

	master	this branch
guideline = TRUE	4 labels, 4 colours	identical
guideline = FALSE	error, nothing drawn	2 labels, 2 colours

With guideline = TRUE both builds pass the same four labels: min StdDev Portfolio, min ES Portfolio, % Increase in Risk = 10.44, % Increase in Return = 11.78.

Tests

None added, none changed. tests/testthat/test-charts-roi.R already asserts
this behaviour in two tests, chart.EfficientFrontierCompare: guideline=FALSE produces no error and chart.EfficientFrontierCompare: legend.loc non-NULL branch produces no error, and both currently fail.

test-charts-roi.R	PASS	FAIL
master	67	2
this branch	69	0

Test suite

	PASS	FAIL	ERROR
master	3550	2	2
this branch	3552	0	2

No failures left. The two errors are the objective() tests in
test-objective-branches.R, which #61 fixes; measured there, that file
goes to 33 passing with none. The two changes touch different files, so between
them the four problems run-all.R reports are accounted for.

Why this one and #61 are worth taking first

R-CMD-check and test-coverage have both been red on master since 24 July,
and both die at the same step, running the tests in 'run-all.R' failed. What
run-all.R reports there is four problems: the two fixed here, and two in
test-objective-branches.R, where ROI masks objective() in a full-suite
run. #61 fixes those.

With both merged, that step passes and the pipeline is green again. I can only
see that the workflows stop at that step, so if something else is broken behind
it, it is hidden by these four rather than absent.

This matters for the five pull requests that are already open, because their
checks are red for this reason and not for theirs. They do not need rebasing:
the workflows run on pull_request and actions/checkout@v4 checks out the
merge commit, so once master carries these two fixes, re-running the jobs on
each of them is enough.

Scope

One file, 7 insertions, of which 6 are the comment. This change stands on its
own and does not depend on any other.

🤖 Generated with Claude Code

[Copilot]

🟢 Approval recommended

The change resolves the reported error while preserving existing guideline behavior.

Pull request overview

Fixes chart.EfficientFrontierCompare() when guideline = FALSE and default legend labels are used.

Changes:

• Initializes create.legend.labels to NULL.
• Preserves guideline labels and keeps legends aligned with plotted frontiers.

File summaries

File	Description
R/charts.efficient.frontier.R	Prevents the missing-object error during legend construction.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Lite

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