Automatically coloring a large number of polygons in CartoDB

Question

I see that I can use the CartoDB wizard to color polygons I have based on a column value. This works great except that it only colors 6 or so polygons and the rest are lumped as “others”.

I see that I can edit the CSS and add the other polygons one at a time. My map has about 250 of these, so doing it one at a time isn’t practical. Is there a more automated way to, say, randomly assign a color from the palette to all the polygons based on a value in the table? It’s fine if there are duplicate colors.

Answer 1

I don't know if there is an elegant way to do that but there is a workaround for it using SQL and CartoCSS:

1) apply a query like

select *, cartodb_id%PALETTE_COLOR_NUMER as pal from your_table

2) apply a cartocss like this:

#layer { ... 
[pal = 0] { polygon-fill: color1; } 
[pal = 1] { polygon-fill: color2; } 
[pal = 2] { polygon-fill: color3; } 
[pal = 3] { polygon-fill: color4; }
[pal = 4] { polygon-fill: color5; }
 ...
}

Answer 2

I wrote a little script for this that solves the problem by generating all the CSS properties that you can then cut and paste into CartDB:

for (rep = 1; rep <= 800; rep++) {
var color = Math.floor(Math.random()*16777215).toString(16);
if (rep < 10)  {
document.write('#mydiv[territory="T00' + rep + '"] {<br> polygon-fill:#' +color+';<br>}<br>');
}
  if (rep >=10 && rep <100)
 {
document.write('#mydiv[territory="T0' + rep + '"] {<br> polygon-fill:#' +color+';<br>}<br>');
}
if (rep >= 100)  {
document.write('#mydiv[territory="T' + rep + '"] {<br> polygon-fill:#' +color+';<br>}<br>');
}
}

The extra if statements were necessary in my case because I had territories formatted like this "T001" and "T099".