CODEWITHSUNDEEP
javascriptdc.jscrossfilter
user3050590
user3050590

Reputation: 1716

dc.js: how to reduceCount on an object element list?

I have an object like:

[    { "Project": 1;  "key":["a", "b", "c", "d"]},
     { "Project": 2;  "key":["b", "c", "d"]},
     { "Project": 3;  "key":["e", "c", "a"]},
     { "Project": 4;  "key":["b", "a", "e", "f"]}        
 ]

so far as I have implemented, reduceCount only counts the occurrence of single element value. I want to change it into something 

key     value
a        3
b        3
c        3
d        2
e        2
f        1

I want to count it on the times it appear in an individual project like "a" has appeared in 3 projects. Actually this data I want to use in my wordcloud.

I can do this outside crossfilters but not sure how can I achieve this through crossfilters dimensions.

Any assistance is appreciable.

SOLUTION as referred by Ethan Jewett

Is there a way to tell crossfilter to treat elements of array as separate records instead of treating whole array as single key?

Upvotes: 1

Views: 144

Answers (1)

Ethan Jewett
Ethan Jewett

Reputation: 6010

If you want to do this in the current version of Crossfilter, you need to use groupAll. The answer to this question provides an example: Is there a way to tell crossfilter to treat elements of array as separate records instead of treating whole array as single key?

Alternatively, you could the Reductio library, which provides a way to generating reduce functions for complex groups very easily, and in this case wraps the groupAll in such a way that it is compatible with dc.js. The relevant section of the documentation is here: https://github.com/crossfilter/reductio#aggregations-groupall-aggregations-reductio-b-groupall-b-i-groupingfunction-i-

If you are feeling especially adventurous, you can try using the master branch of the Crossfilter fork at https://github.com/crossfilter/crossfilter. We have recently added a new parameter to the dimension call that will cause it to treat your data exactly as you describe. Documentation is here: https://github.com/crossfilter/crossfilter/wiki/API-Reference#dimension

Upvotes: 2

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