d3.nest- 分层地分组数组元素。
nest.entries- 返回一组键-值元组
nest.key- 在嵌套层级中添加一个级别。
nest.map- 返回一个关联数组。
nest.rollup- 为叶子值指定一个汇总函数。
nest.sortKeys- 按照键排序叶子嵌套级别。
nest.sortValues- 按照值排序叶子嵌套级别。
Examples
data.csv
Symbol,Price,Date,Time,Change,Volume
"AA",39.48,"6/11/2007","9:36am",-0.18,181800
"AIG",71.38,"6/11/2007","9:36am",-0.15,195500
"CAT",62.58,"6/11/2007","9:36am",-0.46,935000
"AA",98.31,"6/11/2007","9:36am",+0.12,104800
"CAT",53.08,"6/11/2007","9:36am",-0.25,360900
"CAT",78.29,"6/11/2007","9:36am",-0.23,225400
Simple one level nest
