analytics-metrics

What this skill does

# Analytics & Metrics Dashboards

Build data visualization components with Recharts.

## Quick Start

```bash
npm install recharts
```

## Line Chart

```tsx
import {
  LineChart,
  Line,
  XAxis,
  YAxis,
  CartesianGrid,
  Tooltip,
  Legend,
  ResponsiveContainer,
} from 'recharts';

const data = [
  { month: 'Jan', revenue: 4000, users: 2400 },
  { month: 'Feb', revenue: 3000, users: 1398 },
  { month: 'Mar', revenue: 2000, users: 9800 },
  { month: 'Apr', revenue: 2780, users: 3908 },
];

function RevenueChart() {
  return (
    <ResponsiveContainer width="100%" height={400}>
      <LineChart data={data}>
        <CartesianGrid strokeDasharray="3 3" />
        <XAxis dataKey="month" />
        <YAxis />
        <Tooltip />
        <Legend />
        <Line
          type="monotone"
          dataKey="revenue"
          stroke="#3b82f6"
          strokeWidth={2}
        />
        <Line
          type="monotone"
          dataKey="users"
          stroke="#10b981"
          strokeWidth={2}
        />
      </LineChart>
    </ResponsiveContainer>
  );
}
```

## Bar Chart

```tsx
import { BarChart, Bar, XAxis, YAxis, Tooltip, ResponsiveContainer } from 'recharts';

function SalesChart({ data }) {
  return (
    <ResponsiveContainer width="100%" height={300}>
      <BarChart data={data}>
        <XAxis dataKey="name" />
        <YAxis />
        <Tooltip />
        <Bar dataKey="sales" fill="#3b82f6" radius={[4, 4, 0, 0]} />
      </BarChart>
    </ResponsiveContainer>
  );
}
```

## KPI Card

```tsx
interface KPICardProps {
  title: string;
  value: string | number;
  change: number;
  trend: 'up' | 'down';
  icon?: React.ReactNode;
}

function KPICard({ title, value, change, trend, icon }: KPICardProps) {
  const isPositive = trend === 'up';
  
  return (
    <div className="bg-white rounded-lg p-6 shadow-sm border">
      <div className="flex items-center justify-between">
        <p className="text-sm font-medium text-gray-500">{title}</p>
        {icon && <div className="text-gray-400">{icon}</div>}
      </div>
      
      <div className="mt-2">
        <p className="text-3xl font-semibold text-gray-900">{value}</p>
        
        <div className="mt-2 flex items-center">
          <span
            className={`text-sm font-medium ${
              isPositive ? 'text-green-600' : 'text-red-600'
            }`}
          >
            {isPositive ? '↑' : '↓'} {Math.abs(change)}%
          </span>
          <span className="ml-2 text-sm text-gray-500">vs last period</span>
        </div>
      </div>
    </div>
  );
}
```

## Dashboard Layout

```tsx
function Dashboard() {
  return (
    <div className="p-6 space-y-6">
      {/* KPI Grid */}
      <div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-4 gap-4">
        <KPICard
          title="Total Revenue"
          value="$45,231"
          change={12.5}
          trend="up"
        />
        <KPICard
          title="Active Users"
          value="2,345"
          change={8.2}
          trend="up"
        />
        <KPICard
          title="Conversion Rate"
          value="3.2%"
          change={-2.1}
          trend="down"
        />
        <KPICard
          title="Avg. Order Value"
          value="$142"
          change={5.4}
          trend="up"
        />
      </div>

      {/* Charts Grid */}
      <div className="grid grid-cols-1 lg:grid-cols-2 gap-6">
        <div className="bg-white rounded-lg p-6 shadow-sm border">
          <h3 className="text-lg font-medium mb-4">Revenue Over Time</h3>
          <RevenueChart />
        </div>
        
        <div className="bg-white rounded-lg p-6 shadow-sm border">
          <h3 className="text-lg font-medium mb-4">Sales by Category</h3>
          <SalesChart data={salesData} />
        </div>
      </div>
    </div>
  );
}
```

## Pie Chart

```tsx
import { PieChart, Pie, Cell, Tooltip, Legend, ResponsiveContainer } from 'recharts';

const COLORS = ['#3b82f6', '#10b981', '#f59e0b', '#ef4444'];

function DistributionChart({ data }) {
  return (
    <ResponsiveContainer width="100%" height={300}>
      <PieChart>
        <Pie
          data={data}
          cx="50%"
          cy="50%"
          innerRadius={60}
          outerRadius={100}
          dataKey="value"
          label
        >
          {data.map((_, index) => (
            <Cell key={index} fill={COLORS[index % COLORS.length]} />
          ))}
        </Pie>
        <Tooltip />
        <Legend />
      </PieChart>
    </ResponsiveContainer>
  );
}
```

## Formatting Utilities

```typescript
export function formatNumber(value: number): string {
  if (value >= 1_000_000) {
    return `${(value / 1_000_000).toFixed(1)}M`;
  }
  if (value >= 1_000) {
    return `${(value / 1_000).toFixed(1)}K`;
  }
  return value.toLocaleString();
}

export function formatCurrency(value: number, currency = 'USD'): string {
  return new Intl.NumberFormat('en-US', {
    style: 'currency',
    currency,
    minimumFractionDigits: 0,
    maximumFractionDigits: 0,
  }).format(value);
}

export function formatPercent(value: number): string {
  return `${value >= 0 ? '+' : ''}${value.toFixed(1)}%`;
}
```

## Resources

- **Recharts**: https://recharts.org
- **D3.js**: https://d3js.org