# Bar chart

This chart shows the relative frequency of letters in the English language. A vertical bar chart such as this is sometimes called a *column* chart. Data: *Cryptological Mathematics*, Robert Lewand

```js echo
// Declare the chart dimensions and margins.
const width = 928;
const height = 500;
const marginTop = 30;
const marginRight = 0;
const marginBottom = 30;
const marginLeft = 40;

// Declare the x (horizontal position) scale.
const x = d3.scaleBand()
    .domain(d3.groupSort(data, ([d]) => -d.frequency, (d) => d.letter)) // descending frequency
    .range([marginLeft, width - marginRight])
    .padding(0.1);

// Declare the y (vertical position) scale.
const y = d3.scaleLinear()
    .domain([0, d3.max(data, (d) => d.frequency)])
    .range([height - marginBottom, marginTop]);

// Create the SVG container.
const svg = d3.create("svg")
    .attr("width", width)
    .attr("height", height)
    .attr("viewBox", [0, 0, width, height])
    .attr("style", "max-width: 100%; height: auto;");

// Add a rect for each bar.
svg.append("g")
    .attr("fill", "steelblue")
  .selectAll()
  .data(data)
  .join("rect")
    .attr("x", (d) => x(d.letter))
    .attr("y", (d) => y(d.frequency))
    .attr("height", (d) => y(0) - y(d.frequency))
    .attr("width", x.bandwidth());

// Add the x-axis and label.
svg.append("g")
    .attr("transform", `translate(0,${height - marginBottom})`)
    .call(d3.axisBottom(x).tickSizeOuter(0));

// Add the y-axis and label, and remove the domain line.
svg.append("g")
    .attr("transform", `translate(${marginLeft},0)`)
    .call(d3.axisLeft(y).tickFormat((y) => (y * 100).toFixed()))
    .call(g => g.select(".domain").remove())
    .call(g => g.append("text")
        .attr("x", -marginLeft)
        .attr("y", 10)
        .attr("fill", "currentColor")
        .attr("text-anchor", "start")
        .text("↑ Frequency (%)"));

// Display the SVG element.
display(svg.node());
```

```js echo
const data = FileAttachment("/data/alphabet.csv").csv({ typed: "auto" });
```