在AMChart v4中，可以通过设置column.width属性来按数据系列设置柱状图的宽度。以下是一个示例代码：

// 导入AMChart v4模块
import * as am4core from "@amcharts/amcharts4/core";
import * as am4charts from "@amcharts/amcharts4/charts";
import am4themes_animated from "@amcharts/amcharts4/themes/animated";

// 使用动画主题
am4core.useTheme(am4themes_animated);

// 创建图表实例
var chart = am4core.create("chartdiv", am4charts.XYChart);

// 设置数据
chart.data = [{
  category: "A",
  value1: 10,
  value2: 20
}, {
  category: "B",
  value1: 20,
  value2: 30
}, {
  category: "C",
  value1: 30,
  value2: 10
}];

// 创建类别轴
var categoryAxis = chart.xAxes.push(new am4charts.CategoryAxis());
categoryAxis.dataFields.category = "category";

// 创建值轴
var valueAxis = chart.yAxes.push(new am4charts.ValueAxis());

// 创建柱状图系列1
var series1 = chart.series.push(new am4charts.ColumnSeries());
series1.name = "Series 1";
series1.dataFields.valueY = "value1";
series1.dataFields.categoryX = "category";
series1.columns.template.width = am4core.percent(60); // 设置柱状图宽度

// 创建柱状图系列2
var series2 = chart.series.push(new am4charts.ColumnSeries());
series2.name = "Series 2";
series2.dataFields.valueY = "value2";
series2.dataFields.categoryX = "category";
series2.columns.template.width = am4core.percent(40); // 设置柱状图宽度

// 创建图例
chart.legend = new am4charts.Legend();

// 更新图表样式
chart.responsive.enabled = true;

// 渲染图表
chart.render();

在上述代码中，我们通过设置column.width属性来设置柱状图的宽度。am4core.percent(60)表示60%的宽度，am4core.percent(40)表示40%的宽度。你可以根据需要调整这些值来满足你的需求。