# How to create an array of circles within a circle?

I'm looking to place exactly 750 filled circles in a random array within a circular shape, essentially a static version of this infographic

I've considered scatter graphs (but that seems as painful as manually placing each circle), the transform effect and blend tools (but these seem linear, or require going along, rather within a path). I wonder whether I need to script this, but I've never done that before so would love it if you could step out exactly how I should go about this?

One user has suggested making a custom brush, however this does not allow me to specify an exact number of circles (I need to be sure there are 750). One thing I didn't mention earlier is that I want to select and alter the colour of 162 of the circles once they've been drawn, so they need to remain editable.

• That's a good link Scott, but it doesn't give me the ability to specify exactly the number of circles I need. I've edited my question to clarify the difference. Sep 30, 2014 at 0:37
• I'm afraid the answer by plainclothes is as close as you'll get: graphicdesign.stackexchange.com/a/13688/3270 Illustrator offers no internal feature for auto-scattering a defined number of objects within a defined area (other than a scatter graph). Sep 30, 2014 at 0:56
• there is a good step trough for a programming approach on mathematica stackexhange. Sep 30, 2014 at 11:38
• You could calculate the area Y of a square with width X where X is the diameter of a circle with area 750, make a square of Y circles, draw a circle over it and then delete everything not in the circle (using pathfinder?). Just a thought. Sep 30, 2014 at 13:25

## Particle System

My approach would be using a particle generator. But the only ones I know are for 3D images.

So I would use Blender, where you can define the number of particles.

As you need to change the color of some of them I would create two base objects (an object is the shape of the particle that will be repeated) to make two particle systems.

One system with 162 and the other with 588.

Then I would choose a self illuminated material for the particles and the container so my final render looks flat.

If you need a "white" separation you can prepare a fresnel material. This makes the material look one color if the angle is paralel to the camera and the color changes if the angle of this surface changes.

Look for a specific tutorial on how to achieve this: https://www.google.com/search?q=blender+particle+systems

To be sure you have the exact amount of particles generate a lower number of them so you can count them and confirm.

If you "drop" them form some height you will have some randomness in the distribution.

You can render this of a decent size. But if you leave a gap between the circles you could try to trace them.

## Spray it

Another way to do it is using the "Spray" tool inside of Illustrator.

The basic idea is that you prepare a symbol of a circle, choose the spray tool and... spray.

At any moment you can select all the objects in one layer to make an automated counting. (Document info)

You could prepare different layers lets say each with 50 objects so you can keep track on how many objects are there.

The drawback of this method is that some circles can be overlapped one on top of another.

I realise this question is old now, but nevertheless, it seemed like it would be a good challenge to work on an answer, by going into further detail in one of the suggestions @Rafael made in his answer.

1. Create a symbol - a simple circle, with a stroke and a fill (or no stroke if you prefer). Click and drag it into the Symbols palette - and give it a new name.

2. Use the Symbol Sprayer Tool - then in the Symbols palette, choose the symbol you created. Double click the tool to bring up its settings. If you select the intensity and density of the tool correctly, the dots won't overlap. You may have to experiment with the settings to get it to work right.

3. Click `Window` > `Document Info`, and select the `Objects` view from the menu.

4. Click `Object` > `Expand` to expand the symbol set from time to time, then in the Document Info window you will see how many Symbol Instances there are.

5. Undo the Expand using CTRL+Z (undo). This turns it back into a symbol set. Continue spraying into the middle of the symbol set to add more dots.

6. Keep checking the number as before by repeating steps 4 and 5 from time to time. As you approach the number required, click fewer times between checking the numbers with the Expand trick as before. If you are really close to that number, click one at a time, until you have the exact number required. If you overshoot, you can use CTRL+Z to undo.

7. When you have finished, click `Object` > `Expand` two times. This will turn all the symbols into objects.

8. For colouring the dots, click `Object` > `Live Paint` > `Make` - and then `Select` > `Deselect`.

9. Use the Live Paint Bucket to fill in the dots with different colours. To do that, choose a fill colour, mouse over the dot you want to change and click inside it. You can even click and drag the Live Paint Bucket to apply it to several dots at a time.

Here's an example I created using the techniques above. I used it to make 550 dots exactly. Note I used guides to mark the middle of the circle so I could keep spraying symbols in exactly the same spot every time.

• I'm not an Illustrator user, but how did you get the circles so perfectly distributed, i.e. without overlaps? Aug 13, 2018 at 8:16
• @filip Read step 2 in the answer Aug 13, 2018 at 8:20

What about putting 750 • bullets characters in a circle text frame?

To get an irregular distribution, set a different baseline distance to the first two characters and copy/paste them until get 750 characters.

Change the colors automatically outlining the text, ungrouping and using this script

This was an interesting problem so I wrote a small script to generate a circle with a specified number of smaller circles inside it. You can play around with it here:

https://jsfiddle.net/filipux/uL0q1x6g/