{"id":23608,"date":"2021-05-15T18:50:56","date_gmt":"2021-05-16T01:50:56","guid":{"rendered":"https:\/\/www.podfeet.com\/blog\/?p=23608"},"modified":"2021-05-21T15:30:06","modified_gmt":"2021-05-21T22:30:06","slug":"knit-like-a-programmer","status":"publish","type":"post","link":"https:\/\/www.podfeet.com\/blog\/2021\/05\/knit-like-a-programmer\/","title":{"rendered":"Knit Like a Programmer"},"content":{"rendered":"

After I had written most of this article, I realized that I may have come up with a subject that interests absolutely no one but me. You see, this is about knitting like a programmer. How many of you both program, and knit? I mentioned this problem to Bart and he explained that there\u2019s a long history of the intersection of programming and textiles. Bart went on to explain that programming punch cards have their origins in weaving.<\/p>\n

He pointed me to a Wikipedia article about the Jacquard machine, which was designed to program a loom to automate the process of weaving. From the Wikipedia article about the Jacquard machine<\/a>:<\/p>\n

\n The machine was controlled by a “chain of cards”; a number of punched cards laced together into a continuous sequence. Multiple rows of holes were punched on each card, with one complete card corresponding to one row of the design.\n<\/p><\/blockquote>\n

So maybe this intersection of programming and knitting will be of some interest after all.<\/p>\n

I\u2019ve been programming for a few years now, but I\u2019ve been knitting since I was very young. I actually taught myself to knit when I was around 9 years old, learning from a book. I can distinctly remember learning the stockinette stitch at the kitchen table and being SO frustrated until I figured out that the dumb instructions didn\u2019t tell you to move the yarn from back to front to back as you switch from knit to purl and back again. Once I figured that out it was smooth sailing.<\/p>\n

I haven\u2019t knit for a very long time, keeping my fingers busy with crocheting and cross-stitching for at least the last 25 years. But my daughter-in-law Nikki chose a knitted pattern for the baby blanket I’m making for my future grandson. It was time to get back into the game.<\/p>\n

The Problem to be Solved<\/h3>\n
\"Photo
Photo of the Actual Desired Blanket<\/figcaption><\/figure>\n

Execution of some knitting patterns wouldn\u2019t benefit from thinking like a programmer, but the particular pattern I\u2019m working on cries out for it. Knitting patterns (and crochet patterns for that matter) will give you row by row instructions, but whenever a complex bit is repeated, they\u2019ll often throw an asterisk on either side and say \u201crepeat from * to *\u201d.<\/p>\n

In programming, if you\u2019re going to repeat something, you make it a function so you can repeat it predictably. Already we can see that knitting and programming have something in common.<\/p>\n

The problem I was trying to solve was that this pattern is written in a very complicated way. This resulted in constant mistakes on my part until I started to break the pattern down in a different way.<\/p>\n

If you look at the photo on the cover of the instructions, you see an alternating pattern of big square blocks. Every other big square block is either checked or striped, and there are four big rows of blocks. The instructions call these big rows of blocks \u201csets\u201d. So on the first set, it\u2019s blocks of check\/stripe\/check\/stripe, but on set two it\u2019s stripe\/check\/stripe\/check.<\/p>\n

That photo is critical<\/em> to figuring out the pattern, because down in the weeds of the instructions, it’s very difficult to see this big picture view I’ve described.<\/p>\n

\"Knitting
Knitting Pattern as Written<\/figcaption><\/figure>\n

The pattern describes the sets in a very complex way. Let\u2019s say you\u2019re on row 26.<\/p>\n

Row 26 isn\u2019t explicitly explained. It says that row 26 is row 21 in the check pattern. Ok, what\u2019s row 21? Well, row 21 is a repeat of row 1 in the check pattern. I\u2019m not making this up.<\/p>\n

I started by creating two lookup tables but it was like doing two coordinate transformations in your head! I tore out many rows many times.<\/p>\n

That\u2019s when I started to think of it as functions and it became much clearer to me.<\/p>\n

Let\u2019s think of the check and stripe blocks as functions, because inside each of those blocks, we have a set of instructions. We\u2019re going to call them stripeBlock and checkBlock.<\/p>\n

function stripeBlock() {do stripe-type stuff}<\/code><\/p>\n

function checkBlock() {do check-type stuff}<\/code><\/p>\n

StripeBlock<\/h3>\n