Counting arrays in D3 and getting that number to visualise map points

Question

I am making cartographic visualisation in D3 with topoJson. I have visualised cities as points with a given radius. However, I want to see this attribute based on how many values I have there (let's say kindergartens in each city) - that is for Glasgow 57, Dundee 26.

So I just need to count how many arrays are there in the values. I have searched but have not found any suitable solution.

        enterSelection
           .append("circle")
           .attr("r", 4);

EDIT: Need to update the 4 in the code below. If I am using tip given in comments, it gives me only the radius in the size of the array of the specific city (but I need different radius for each city) Tried to change attribute to

.attr("r", d=>(d.town.values.length))

but that gives me Uncaught TypeError: Cannot read property 'values' of undefined error

@TilakMaddy I am using it in the code when I am setting up the radius of each point in here: enterSelection .append("circle") .attr("r", towns[1].values.length); (added to the question) but then I get only the radius of specific city. — mrakoplas, Jul 04 '20 at 13:51
@TilakMaddy When I am using the console, it works when typing towns.map(d => d.values.length — mrakoplas, Jul 04 '20 at 14:32
@TilakMaddy I found out (viz. solution) but thanks for pointing me at the direction — mrakoplas, Jul 04 '20 at 14:40

mrakoplas · Accepted Answer · 2020-07-05T00:37:16.010

-2

This is the solution that worked.

enterSelection
                .append("circle")
                .attr("r", d => d.values.length)

edited Jul 05 '20 at 00:37

answered Jul 04 '20 at 14:40

mrakoplas

94
8

Counting arrays in D3 and getting that number to visualise map points

1 Answers1