Counting distinct values from JSON using D3.nest() - d3.js

Question

I have a following JSON:
{
"ReturnCode":0,
"ReturnMessage":"Success",
"List":[{
"Client":"Ad",
"Department":"DP",
"ProjectId":"12355",
"ProjectName":"4940"
}, {
"Client":"Ad",
"Department":"SP",
"ProjectId":"12355",
"ProjectName":"4940"
}, {
"Client":"Ad",
"Department":"Co",
"ProjectId":"12355",
"ProjectName":"asdf"
}, {
"Client":"Ad",
"Department":"Co",
"ProjectId":"212355",
"ProjectName":"45ed"
}, {
"Client":"Ad",
"Department":"Co",
"ProjectId":"212355",
"ProjectName":"45ed "
}, {
"Client":"we",
"Department":" SP ",
"ProjectId":"123455",
"ProjectName":"asdf"
}, {
"Client":"we",
"Department":"Co",
"ProjectId":"123455",
"ProjectName":"asdf"
}, {
"Client":"oc",
"Department":"Co",
"ProjectId":"24355",
"ProjectName":"qwe"
}]
}
I just need to count the number of projects to each client like below using d3.nest:
[{Key:”Ad”, value:2}, {Key:”we”, value:1}, {Key:”oc”, value:1}]

Answer 1

look at d3.nest() link it has many examples for rolling up for d3.nest() function. For your case you can do something like code written below.
d3.json("json/data.json", function(data) {
console.log(data);
var nested_data = d3.nest()
.key(function(d) { return d.Client; })
.key(function(d) { return d.ProjectId; })
.rollup(function(leaves) { return leaves.length; })
.entries(data.List);
console.log(nested_data);
console.log(nested_data[0].values.length) //length of key 'AD'
})

Answer 2

Try this way.
var obj = {
"ReturnCode":0,
"ReturnMessage":"Success",
"List":[{
"Client":"Ad",
"Department":"DP",
"ProjectId":"12355",
"ProjectName":"4940"
}, {
"Client":"Ad",
"Department":"SP",
"ProjectId":"12355",
"ProjectName":"4940"
}, {
"Client":"Ad",
"Department":"Co",
"ProjectId":"12355",
"ProjectName":"asdf"
}, {
"Client":"Ad",
"Department":"Co",
"ProjectId":"212355",
"ProjectName":"45ed"
}, {
"Client":"Ad",
"Department":"Co",
"ProjectId":"212355",
"ProjectName":"45ed "
}, {
"Client":"we",
"Department":" SP ",
"ProjectId":"123455",
"ProjectName":"asdf"
}, {
"Client":"we",
"Department":"Co",
"ProjectId":"123455",
"ProjectName":"asdf"
}, {
"Client":"oc",
"Department":"Co",
"ProjectId":"24355",
"ProjectName":"qwe"
}]
};
var nested_data = d3.nest()
.key(function(d) { return d.Client; })
.key(function(d) { return d.ProjectId; })
.rollup(function(leaves) { return leaves.length; })
.entries(obj.List)
.map(function(d){
var ob = {};
ob.Key = d.key;
ob.value = d.values.length;
return ob;
});
alert(JSON.stringify(nested_data));
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>
Output:
[{
"Key": "Ad",
"value": 2
}, {
"Key": "we",
"value": 1
}, {
"Key": "oc",
"value": 1
}]

Answer 3

for the last part i would simply use ----
for (var item in nested_data) {
console.log(nested_data[item].key+'--'+ Object.keys(nested_data[item].values).length);
}