# Select Extrema

> Line chart automatically pinpointing and labeling high/low extrema points.

A shadcn/ui block from the [@paceui](https://paceui.com/?utm_source=shadcn.exchange) registry, listed on [shadcn.exchange](https://shadcn.exchange/r/paceui/tanstack-charts-select-extrema).

- Page, with a live preview: https://shadcn.exchange/r/paceui/tanstack-charts-select-extrema
- Screenshot: https://abzjhwgwpdpz7ua5.public.blob.vercel-storage.com/shots/paceui/tanstack-charts-select-extrema-light-984eed54bc7984c0.png
- Registry item: https://paceui.com/r/tanstack-charts-select-extrema.json
- Listed: 2026-10-21, source last changed 2026-10-21

## Install

```bash
npx shadcn@latest add https://shadcn.exchange/r/paceui/tanstack-charts-select-extrema.json
```

Run it in a project that has shadcn/ui set up. It adds the files below and installs what they depend on.

## Dependencies

- npm packages: `@tanstack/charts`, `@tanstack/react-charts`, `d3-scale`
- Registry items: `card`

## Files

### `components/tanstack-charts/line/select-extrema.tsx`

```tsx
import { type ChartPoint, defineChart, dot, lineY, select, text } from "@tanstack/charts";
import { decorative } from "@tanstack/charts/mark/decorative";
import { motion } from "@tanstack/charts/motion";
import { tooltip } from "@tanstack/charts/tooltip";
import { Chart } from "@tanstack/react-charts/core";
import { useMemo } from "react";

import { scaleLinear, scaleUtc } from "d3-scale";
import { ArrowUpRight } from "lucide-react";

import { Card, CardContent, CardDescription, CardFooter, CardHeader, CardTitle } from "@/components/ui/card";

interface StockDatum {
    Date: Date;
    Close: number;
}

const motionRenderer = motion({
    initial: "always",
    transition: { type: "spring", stiffness: 170, damping: 18, mass: 1 },
});

function generateDemoData(): StockDatum[] {
    const results: StockDatum[] = [];
    let price = 140;

    for (let d = 0; d < 60; d++) {
        const date = new Date(Date.UTC(2024, 0, 1 + d));
        price += Math.sin(d * 0.15) * 3 + (Math.random() - 0.48) * 4;
        price = Math.max(100, Math.min(220, price));
        results.push({ Date: date, Close: Number(price.toFixed(2)) });
    }
    return results;
}

function shadcnTooltipContent<TDatum>(points: readonly ChartPoint<TDatum>[]) {
    if (points.length === 0) return { title: "", rows: [] };
    const d = points[0].datum as StockDatum;
    if (!d || !d.Date) return { title: "", rows: [] };
    const dateObj = d.Date instanceof Date ? d.Date : new Date(d.Date);
    const titleStr = isNaN(dateObj.getTime())
        ? ""
        : dateObj.toLocaleDateString("en-US", { month: "short", day: "numeric", year: "numeric", timeZone: "UTC" });
    return {
        title: titleStr,
        rows: [{ label: "Closing Price", value: `$${d.Close.toFixed(2)}`, color: "var(--chart-1)" }],
    };
}

export function SelectExtrema() {
    const data = useMemo(() => generateDemoData(), []);

    const minimumPoint = useMemo(
        () =>
            select(data, {
                value: "Close",
                select: "min",
            }),
        [data],
    );

    const maximumPoint = useMemo(
        () =>
            select(data, {
                value: "Close",
                select: "max",
            }),
        [data],
    );

    const definition = useMemo(
        () =>
            defineChart(
                {
                    renderer: motionRenderer,
                    marks: [
                        lineY(data, {
                            id: "close-line",
                            x: "Date",
                            y: "Close",
                            key: (row: StockDatum) =>
                                row?.Date
                                    ? row.Date instanceof Date
                                        ? row.Date.getTime()
                                        : new Date(row.Date).getTime()
                                    : 0,
                            stroke: "var(--chart-1)",
                            strokeWidth: 2.25,
                        }),
                        dot(minimumPoint, {
                            id: "minimum-point",
                            x: "Date",
                            y: "Close",
                            fill: "var(--destructive)",
                            r: 5,
                        }),
                        dot(maximumPoint, {
                            id: "maximum-point",
                            x: "Date",
                            y: "Close",
                            fill: "var(--emerald-500, #10b981)",
                            r: 5,
                        }),
                        decorative(
                            text(minimumPoint, {
                                id: "minimum-label",
                                x: "Date",
                                y: "Close",
                                text: ({ Close }: StockDatum) => `Low $${Close.toFixed(2)}`,
                                fill: "var(--destructive)",
                                anchor: "middle",
                                dy: 15,
                                fontSize: 10,
                                fontWeight: 700,
                            }),
                        ),
                        decorative(
                            text(maximumPoint, {
                                id: "maximum-label",
                                x: "Date",
                                y: "Close",
                                text: ({ Close }: StockDatum) => `High $${Close.toFixed(2)}`,
                                fill: "var(--emerald-500, #10b981)",
                                anchor: "middle",
                                dy: -15,
                                fontSize: 10,
                                fontWeight: 700,
                            }),
                        ),
                    ],
                    scales: {
                        x: { scale: scaleUtc, axis: { label: "Date Timeline" } },
                        y: {
                            scale: scaleLinear,
                            grid: true,
                            axis: { label: "Stock Closing Price ($ USD)" },
                        },
                    },
                    margin: { top: 28, right: 24, bottom: 32, left: 45 },
                    theme: {
                        foreground: "var(--muted-foreground)",
                        grid: "var(--border)",
                        background: "transparent",
                    },
                },
                {
                    keyboard: true,
                    tooltip: {
                        use: tooltip,
                        className:
                            "font-sans shadow-none rounded-md bg-popover text-popover-foreground border p-2 text-xs",
                        anchor: "pointer",
                        placement: "auto",
                        content: (points) => shadcnTooltipContent(points),
                    },
                },
            ),
        [data, minimumPoint, maximumPoint],
    );

    return (
        <Card className="w-full max-w-xl">
            <CardHeader>
                <CardTitle>Automatic Extrema High/Low Annotations</CardTitle>
                <CardDescription>
                    Line chart automatically pinpointing and annotating global min & max points
                </CardDescription>
            </CardHeader>
            <CardContent>
                <div className="h-[250px] w-full">
                    <Chart
                        definition={definition}
                        renderer={motionRenderer}
                        height={250}
                        ariaLabel="Automatic Extrema High/Low Annotations Chart"
                    />
                </div>
            </CardContent>
            <CardFooter className="flex-col items-start gap-2 text-sm">
                <div className="flex items-center gap-2 leading-none font-medium">
                    Automatic select reducer isolates high/low extrema values{" "}
                    <ArrowUpRight className="h-4 w-4 text-emerald-500" />
                </div>
                <div className="text-muted-foreground leading-none">
                    Decorative text marks position callout badges dynamically at extreme coordinates
                </div>
            </CardFooter>
        </Card>
    );
}

export default SelectExtrema;
```