React + D3：从数组中的数据渲染条形图

Question

I'm having difficulty rendering a bar chart with d3 (v4) and react.

I'm getting this error

data.map is not a function

data is stored in an array formatted as such:

{
Number:["2", "4", "8"]
Species:["cat", "dog", "rabbit"]
}

Which is passed into BarChart component as a prop:

 <BarChart data={data} />

BarChart.jsx

import React,{ Component } from 'react';
import { scaleBand, scaleLinear } from 'd3-scale';

class BarChart extends Component {

    render() {

      const svgWidth = 960, svgHeight = 500;

      const margin = { top: 20, right: 20, bottom: 30, left: 40 },
          width = svgWidth - margin.left - margin.right,
          height = svgHeight - margin.top - margin.bottom;

      const data = this.props.data;

      const x = scaleBand.domain(data.map(d => d.Species))
                         .rangeRound([0, width])
                         .padding(0.1),

            y = scaleLinear.domain([0, max(data, d => d.Number)])
                           .rangeRound([height, 0]);

      <svg width={svgWidth} height={svgHeight}>
        <g transform={`translate(${margin.left}, ${margin.top})`}>
          {data.map(d => (
            <rect
              x={x(d.Species)}
              y={y(d.Number)}
              width={x.bandwidth()}
              height={height - y(d.frequency)}
            />
          ))}
        </g>
      </svg>
    }
};


export default BarChart;

EDIT:

If I change the format of the object to :

data = [
  {
    Number: '2',
    Species: 'Cat'
  },
  {
    Number: '4',
    Species: 'Dog'
  },
  {
    Number: '8',
    Species: 'Rabbit'
  }];

I get this error:

_d3Scale.scaleBand.domain is not a function

Answer 1

data seems to be an object and not an array. for the code to work, data should be:

data = [
  {
    Number: '2',
    Species: 'Cat'
  },
  {
    Number: '4',
    Species: 'Dog'
  },
  {
    Number: '8',
    Species: 'Rabbit'
  }];