recharts-chart

name: recharts-chart description: Create new Recharts visualization components following the project's proven chart patterns (responsive, typed, dark-mode compatible).

Recharts Chart Skill

Generate new chart components that match the conventions established across the 3 existing Recharts chart types (ROCCurve, CalibrationPlot, MetricsBar) in apps/web/components/charts/.

When to Use

• Adding a new visualization to the Next.js dashboard
• Creating a chart component for a new model metric
• Building single-series or multi-series comparisons

When NOT to Use

• Non-chart UI components (use shadcn/ui patterns instead)
• Custom HTML visualizations like the confusion matrix grid
• Charts that don't use Recharts (e.g., D3-only)

Chart Types Available

Creation Steps

1. Define the TypeScript interface in apps/web/lib/types.ts

   • Match the Pydantic schema structure from shared/schemas/
   • Use arrays for series data (e.g., fpr: number[], tpr: number[])

2. Create the component in apps/web/components/charts/<name>.tsx

   • Follow the template in references/chart-template.tsx
   • Start with "use client" directive
   • Single default or named export

3. Add data transformation (if needed)

   • Transform parallel arrays into Recharts point objects inside the component
   • Keep transformation minimal; prefer shaping data at the page level

4. Integrate into a page

   • Wrap in a <Card> component with a descriptive title
   • Pass typed props from API response data

Conventions

Component Structure

Every chart component follows this order:

"use client";

// 1. Recharts imports (destructured)
import { CartesianGrid, Line, LineChart, ... } from "recharts";

// 2. Type imports
import type { DataType } from "@/lib/types";

// 3. Props interface
interface ChartNameProps { ... }

// 4. Constants (colors, labels)
const COLORS = ["#2563eb", "#dc2626", "#16a34a", "#9333ea", "#ea580c"];

// 5. Component function
export function ChartName({ data }: ChartNameProps) { ... }

Dimensions

• Height: Always 350 via ResponsiveContainer
• Width: Always "100%" via ResponsiveContainer
• Margins (with axis labels): { top: 5, right: 20, bottom: 25, left: 10 }
• Margins (without axis labels): { top: 5, right: 20, bottom: 5, left: 10 }

Color Palette

const COLORS = ["#2563eb", "#dc2626", "#16a34a", "#9333ea", "#ea580c"];
//               blue        red        green      purple     orange

• Primary single-series color: #2563eb
• Multi-series: index into COLORS[idx % COLORS.length]
• Reference lines / guides: #9ca3af (gray-400)

Grid and Axes

<CartesianGrid strokeDasharray="3 3" />

Numeric 0–1 axis (probabilities, rates):

<XAxis
    dataKey="fieldName"
    type="number"
    domain={[0, 1]}
    label={{ value: "Axis Label", position: "insideBottom", offset: -15 }}
/>
<YAxis
    domain={[0, 1]}
    label={{ value: "Axis Label", angle: -90, position: "insideLeft" }}
/>

Categorical axis (metric names, categories):

<XAxis dataKey="category" />
<YAxis domain={[0, 1]} />

Tooltip

Standard formatter for numeric values:

<Tooltip formatter={(value: number | undefined) => value?.toFixed(4) ?? ""} />

With custom label:

<Tooltip
    formatter={(value: number | undefined) => value?.toFixed(4) ?? ""}
    labelFormatter={(label) => `Label: ${Number(label).toFixed(4)}`}
/>

Line Styling

<Line
    name="Series Label"
    type="monotone"
    dataKey="fieldName"
    stroke="#2563eb"
    dot={false}           // false for dense data, { r: 4 } for sparse
    strokeWidth={2}
/>

Reference Lines (diagonal, threshold markers)

<ReferenceLine
    segment={[{ x: 0, y: 0 }, { x: 1, y: 1 }]}
    stroke="#9ca3af"
    strokeDasharray="5 5"
    label="Random"
/>

Data Transformation

Transform parallel arrays into Recharts point objects:

// Input: { fpr: number[], tpr: number[] }
const chartData = data.fpr.map((fpr, i) => ({
    fpr,
    tpr: data.tpr[i],
}));

Pivot models into comparison data:

// Input: models[] with metric fields
const chartData = metrics.map((metric) => {
    const point: Record<string, string | number> = { metric: labels[metric] };
    for (const model of models) {
        point[model.name] = Number(model[metric].toFixed(4));
    }
    return point;
});

Multi-Series (Dynamic)

{items.map((item, idx) => (
    <Line
        key={item.label}
        name={item.label}
        dataKey="y"
        stroke={item.color || COLORS[idx % COLORS.length]}
        dot={false}
        strokeWidth={2}
    />
))}

Checklist

• "use client" directive at top of file
• Props interface defined with proper types
• ResponsiveContainer wrapping with width="100%" and height={350}
• CartesianGrid strokeDasharray="3 3"
• Axes with labels (if applicable) using project conventions
• Tooltip with .toFixed(4) formatter
• Uses project color palette (COLORS array or #2563eb primary)
• Data type added to apps/web/lib/types.ts (if new)
• Component exported as named export
• Integrated into page wrapped in <Card>