我加了你的新代码,但会有error, 说data is not defined.我不知道哪里做错。

d3.csv("data.csv", type, function(data){

console.log(data);

});

function type(d){

d.population = +d.population;

return d;

}

var bar_width = 50,

bar_padding = 10,

svg_width = (bar_width + bar_padding) * data.length,   <-------'data is not defined'

svg_height=500;