xxd-data-viz

Purpose

Use this skill when colors must encode data. It should not turn a poster palette into a chart palette; it must choose colors by data meaning, distinguishability, ordering, and accessibility.

Pain Points This Solves

• Attractive palettes fail charts because categories are not distinct or values are not ordered by lightness.
• Designers mix categorical, sequential, and diverging color logic in one chart.
• Chart color often relies on hue alone, which weakens accessibility and makes legends harder to read.

Data Contract

• This public package is self-contained in SKILL.md; no external color-table files are required.
• Use the proven palettes and color-selection rules documented below as the authoritative contract.
• Do not treat poetic color harmony as chart-ready by default; validate distinctness or ordering for the chart mode.
• Do not rely on hue alone. Add label, order, pattern, stroke, marker shape, direct labeling, or interaction guidance when needed.

Chart Mode Workflow

1. Identify data meaning before picking colors:
   • Categorical: unrelated groups.
   • Sequential: low to high values.
   • Diverging: two directions around a meaningful midpoint.
   • Highlight: one or two emphasized series against quiet context.
   • Dashboard semantic: success, warning, danger, info, selected, neutral.
2. Choose selection criteria:
   • Categorical: maximize hue and lightness separation.
   • Sequential: monotonic lightness is more important than poetic harmony.
   • Diverging: balance perceived strength on both sides and reserve a neutral midpoint.
   • Highlight: keep background series quiet and the target unmistakable.
3. Build the palette from project colors only.
4. Add chart implementation details:
   • Background/grid/axis color.
   • Legend or direct labels.
   • Hover and selection color.
   • Missing data and disabled series.
5. If requested, output ECharts, D3, Chart.js, or CSV arrays.

Output Shape

• Data context: chart type, series count, background, data meaning.
• Mode decision: categorical, sequential, diverging, highlight, or semantic.
• Palette table: order or series, color name, HEX, role, reason.
• Usage rules: legend, labels, grid, hover, selection, missing data.
• Accessibility notes: where labels, markers, strokes, or patterns are required.
• Optional code in the requested chart format.

For charts with more than 12 categories, recommend grouping, sorting, filtering, or interaction rather than forcing more colors.

Proven Palette: 3D UCS Surface + Signed Error

Use this palette when a 3D surface encodes a continuous UCS value and lollipop markers encode signed model error:

from matplotlib.colors import LinearSegmentedColormap

VALUE_CMAP = LinearSegmentedColormap.from_list(
    'ucs_zhongguo_seq',
    [
        '#003152',  # 普鲁士蓝, lowest value
        '#1661AB',  # 靛青
        '#2376B7',  # 花青
        '#1E9EB3',  # 翠蓝
        '#57C3C2',  # 石绿
        '#B6D7A8',  # 松花
        '#F6D58A',  # 杏黄
        '#FFF2B2',  # 乳鸭黄, highest value
    ],
    N=256,
)

POS_BALL = '#D92121'  # 朱砂红, positive error / over-prediction
POS_STEM = '#A61B29'  # 苋菜红
NEG_BALL = '#1A94BC'  # 钴蓝, negative error / under-prediction
NEG_STEM = '#15559A'  # 海涛蓝
COL_SPINE = '#2C2C2C'
COL_GRID = '#DDDDDD'
COL_TEXT = '#1A1A1A'
COL_BG = '#FFFFFF'

Usage rules:

• Treat the surface as sequential data; map low-to-high values through the full blue-cyan-green-yellow ramp.
• The listed stops are ordered by increasing perceived lightness; do not insert a darker warm stop after #B6D7A8 without rechecking monotonicity.
• Treat signed model error as diverging semantic glyph color: warm red for over-prediction and cool blue for under-prediction.
• Add shape/depth cues, not only hue: use lollipop direction, cylinder/sphere glyphs, legend labels, and an overall error range.
• Avoid per-point numeric labels when many lollipops are present; they obscure the surface and reduce accessibility.

Required Inputs

Ask for these if missing:

• chart type and data meaning: categorical, sequential, diverging, highlight, semantic dashboard, map, or interaction state;
• number of series/classes and background color;
• accessibility constraints such as colorblind-safe, grayscale print, direct labels, markers, or patterns;
• target implementation format, if any: Matplotlib, ECharts, D3, Chart.js, CSS, JSON, or CSV.

Output Contract

Return a palette decision that includes:

• data context and chosen palette mode;
• ordered color list with Chinese color name, HEX value, role, and reason;
• usage rules for axes, grid, labels, legend, hover/selection, missing data, and disabled states;
• accessibility notes and optional implementation code in the requested format.

Local Contents

This lightweight skill keeps its reusable palette rules, proven UCS/error palette, input contract, and output contract entirely in this SKILL.md.

• LICENSE and NOTICE.md: retained MIT terms and upstream provenance.