Answers on a postcard please

[Galina]

If I use 6 different coloured yarns to mark my pea crosses and either use one colour or maximum two colours together to mark different crosses, how many different combinations do I get with my yarns?

Just spent half an hour working out that I have 21 combinations on the back of an envelope. And what combinations I have still available as I have already done several crosses and got fed up looking down my sheet every time to check I hadn't used a combination already..

There must be a mathematical way of doing this that is much quicker

[Silverleaf]

I get 27 (in my head, in about 15 seconds)! I don't think you've worked it out wrong, just forgotten that you can have multiples of the same colour (like red and red together).

6 single colours
Every colour combines with all 6 colours (including itself) which would normally be 36 (6x6) combinations, but because in this case red/yellow is the same as yellow/red you need to remove duplicates. This means the first colour has 6 combinations, the second has 5 because you've already counted 1/2, the third only has 4, then 3, then 2, then 1.

So 6 for the singles, and the triangle of 6 for the doubles. Minus 6 if you don't want doubles.

[Galina]

No multiples of the same colour as the old eyes can't distinguish at a glance between one or two of the same colour. That you can just work it out like that is impressive Silverleaf. Wish I had that ability. How do you mark your crosses?

I notice that Mike Ambrose on the youtube video suggests jewellery tags. https://www.youtube.com/watch?v=Pq7-JGRmFBc

[Silverleaf]

That makes sense.

I've used a different method every year to be honest, and haven't settled into one yet. Not sure how I'll do it this year.

That kind of maths is sort of intuitive for me. Anything with stats or probability comes easily - with your question my brain just kind of knew the answer without thinking about it too much. I've always enjoyed messing around with numbers and combinations of stuff like that.

[jayb]

I use coloured silks, strands are easy to separate if you want and they are cheap enough to buy a nice mixed pack of colours (need to be water fast!). Although I've still quite a bagfull left to me by an auntie and my grannie, colours are a bit samey with some. I found jewellery tags get a bit soggy outdoors here, but fine for inside poly tunnel or greenhouse. I like using the colour coding as I can keep a written copy on the computer to refer back too, plus if needed it's easy to keep a printed card with colours used and what they indicate along with a bag of silks and a pair of tweezers!.

[Galina]

Yes it does need to be waterproof, like your silks. I have a plastic food container with my crib sheet little note pad, sharp tweezers and the markers, also a pen to write down any new combination that offers itself. And the information is also in my gardening book, in case the notepad gets lost or blows away. I have to watch which peas to pick as some of the crosses have turned into pods nicely.

[jayb]

Lol, yes the times I've misplaced my planting or crossing list is amazing!!!!
Exciting stuff and hope the critters stay away.

[Galina]

Well yes indeed. We have so many pigeons here, it would be a great shame to lose crossed pods. I probably should repeat all the crosses I made just to be sure to actually get at least one pod.

[Silverleaf]

I like to write on pods with a Sharpie once they are big enough, just as insurance in case I lose the yarn when I harvest them.

[Galina]

I have done that but with an ordinary biro. Are sharpie pens less likely to fade under sunlight.than biros? For plant labels I use pencil which always stays legible, but you can't write onto pods with pencil.

[Silverleaf]

I think I might have tried biro too, but I think both sometimes have to be redone when they fade a bit.

I mostly write on them quite late though so it's not usually a problem.