Scenario value of Chart Maker in line
`line-chart-slide-figure` supports 趋势追踪与波动解释场景. Keep metric consistency, chart-type fit, and destination readability stable with pilot validation, staged rollout, and anomaly logging.
Line charts: fix time grain and gap policy first, then handle missing spikes, then annotate inflection points instead of relying on smoothing polish.
- Decide whether the X axis is every calendar day or trading days only, and whether holiday gaps stay empty or bridge. With more than three series, consider small multiples or sparing secondary axes so five rainbow lines do not become spaghetti under a projector. Align legend order with draw order and protect the right margin for the last label.
- Represent missing values with breaks or dashed segments instead of silent straight bridges; annotate spikes with promo, outage, or backfill notes. Disable animation and heavy smoothing before exporting static PNGs auditors might misread as denser sampling. Avoid dual Y axes by default; if required, state in the title that scales are not comparable.
- Reserve safe space for end markers and legends; preview on mobile dark mode so cyan-green traces do not vanish on OLED. Attach the raw-grain CSV so readers can drill to hourly values and so reviews can match the screenshot.
Line chart FAQ: dual-axis traps, bridged gaps, over-smoothing, overlapping ticks, and missing event notes
We added a second Y axis for revenue and conversion and reviewers say we implied correlation—can that ship externally?
Avoid dual axes by default; if the business mandates them, headline that the scales are independent and not evidence of linkage, or move to scatter and facets. Never scale two series to create faux synchronization. Split charts or cite correlation in a footnote. Regulated industries should treat this as a disclosure risk.
Three missing days were auto-connected and the slope looks like a crash—how do you mark “no observations here”?
Break the line or leave explicit blanks, footnote the outage window, and if you interpolate, name the method and gray out interpolated segments. Capture the raw table screenshot in meeting notes so nobody re-litigates the line later.
We compare year-over-year weeks but leap years misalign ISO week labels—should the axis read W03 or explicit dates?
For executives, prefer concrete date ranges with an ISO-week explainer in the footnote; keep week indices in an appendix. Call out 53-week years. Lock YoY alignment on the release form so nobody rebuilds the chart later with calendar months.
Smoothing makes the curve elegant but trims peaks—screenshots in chat misread the max; is that a visualization bug?
It is a product choice: ship raw and smoothed variants or disable smoothing for external use. Disclose algorithm and window when smoothing stays. For audits use step or point-to-point lines so aesthetics never replace extrema.
Legend colors collapse on a cheap projector and the back row wants phone photos to work—how do you keep brand hues?
Add line patterns (solid, dashed, dot-dash) and end markers beyond color alone; bold the primary series to the minimum legible stroke. Maintain a high-contrast “projection mode” theme in the template library. Rehearse by photographing the slide from the last row.