Crossfilter reduce :: find number of uniques
I am trying to create a custom reduce function for a dataset attribute group that would sum a number of unique values for another attribute.
For example, my dataset looks like a list of actions on projects by team members:
{ project:"Website Hosting", teamMember:"Sam", action:"email" },
{ project:"Website Hosting", teamMember:"Sam", action:"phoneCall" },
{ project:"Budjet", teamMember:"Joe", action:"email" },
{ project:"Website Design", teamMember:"Joe", action:"design" },
{ project:"Budget", teamMember:"Sam", action:"email" }
So, team members work on a variable number of projects by performing one action per line. I have a dimension by team member, and would like to reduce it by the number of projects (uniques).
I tried the below (storing project in a uniques array) without success (sorry, this might hurt your eyes):
var teamMemberDimension = dataset.dimension(function(d) {
return d.teamMember;
});
var teamMemberDimensionGroup = teamMemberDimension.group().reduce(
// add
function(p,v) {
if( p.projects.indexOf(v.project) == -1 ) {
p.projects.push(v.project);
p.projectsCount += 1;
}
return p;
},
// remove
function(p,v) {
if( p.projects.indexOf(v.projects) != -1 ) {
p.projects.splice(p.projects.indexOf(v.projects), 1);
p.projectsCount -= 1;
}
return p;
},
// init
function(p,v) {
return { projects:[], projectsCount:0 }
}
);
Thanks a lot!
Edit after DJ Martin's answer ::
So, to be clearer, I would like to get the numbers I am after here would be:
-----------
Sam : 2 (projects he is workin on, no matter the number of actions)
Joe : 2 (projects he is workin on, no matter the number of actions)
-----------
The answer provided by DJ Martin gets me there. But rather than hard coding a table, I would like to find a way to use these numbers for my DC.JS bar chart. When I was only using the number of actions (so just a reduceCount() ), I did it like below:
teamMemberChart.width(270)
.height(220)
.margins({top: 5, left: 10, right: 10, bottom: 20})
.dimension(teamMemberDimension)
.group(teamMemberDimensionGroup)
.colors(d3.scale.category20())
.elasticX(true)
.xAxis().ticks(4);
I guess there might be something to change in the group().
UPDATED ANSWER
Sorry I misunderstood the question... you are actually on the right track. You'll just need to maintain a count of each project so that your subtract function can know when to remove the value.
teamMemberGroup = teamMemberDimension.group().reduce(
function (p, d) {
if( d.project in p.projects)
p.projects[d.project]++;
else p.projects[d.project] = 1;
return p;
},
function (p, d) {
p.projects[d.project]--;
if(p.projects[d.project] === 0)
delete p.projects[d.project];
return p;
},
function () {
return {projects: {}};
});
Here is an updated fiddle: http://jsfiddle.net/djmartin_umich/3LyhL/
链接地址: http://www.djcxy.com/p/32792.html