g group element doesn't start at 0,0 inside the svg

user_10134463 0
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I am trying d3.js with svelte, and I started to do a simple bar chart, but I am facing an issue I couldn't figure out. The issue, is, the group element g inside the svg element, that contains the bars, is initially shifted from the origin of the svg element (the top left corner). This is the code

<script>
  import * as d3 from 'd3';
  let data = [
    { name: 'Apple', amount: 20 },
    { name: 'Orange', amount: 80 },
    { name: 'Banana', amount: 50 },
    { name: 'Grapes', amount: 10 },
  ];

  let width = 600;
  let height = 400;

  let margins = { top: 20, right: 20, bottom: 100, left: 100 };

  let innerWidth = width - margins.left - margins.right;
  let innerHeight = height - margins.top - margins.bottom;

  const xScale = d3
    .scaleBand()
    .domain(data.map((d) => d.name))
    .range([0, innerWidth])
    .paddingInner(0.1);
  const yScale = d3
    .scaleLinear()
    .domain([0, d3.max(data, (d) => d.amount)])
    .range([innerHeight, 0]);
</script>

<div class="canvas">
  <svg {width} {height}>
    <g>
      {#each data as d}
        <rect
          width={xScale.bandwidth()}
          height={innerHeight - yScale(d.amount)}
          x={xScale(d.name) + xScale.bandwidth() / 2}
          y={yScale(d.amount)}
        />
      {/each}
    </g>
  </svg>
</div>

<style>
  .canvas {
    margin-top: 100px;
    width: 600px;
    height: 400px;
    background-color: #fff;
  }
</style>

I was expecting the group element g to start at (0,0) of the svg element (the top left corner), but it's x-shifted without any transform attribute on the g element. This is messing things up when I try to shift the group element appropriately to add axes later. My question is: why is there initial shift?

Here are the svg and g elements as appear on the screen

enter image description here enter image description here

d3.js svelte svg javascript
1 Answers

Your g is not translated, the bounds of the g merely reflect the bounds of its contents. If the contents aren't bounded by a point at [0,0], the g also won't be bounded by a point at [0,0].

Eyeballing it, I'd say the left most limit of the bars, and therefore the g, is about half the bandwidth from the edge of the SVG. If we look at how you position the bars, that makes sense:

 x={xScale(d.name) + xScale.bandwidth() / 2}

Despite a scaled value of 0 for the first bar, the rectangle is nudged over by half the bandwidth. The placement of the g just reflects the placement of the bars, not a transform.

user_71060860
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