"Rotate" 2D array

[Geppy57]

Hi all.
I'm testing a system with MLX90640 and the image is satisfying.
In order to get a valid application for my specific case, I need to rotate 90 degrees the original matrix to get landscape orientation. (for data, not only for image).
With node-red-contrib-ui-heatmap I see the target with correct 24 columns and 32 rows.
My application need to divide the columns in three groups with 8 columns each in order to verify the maximum temperature in each zone.
Actually I have convert the original 32 x 24 array in a 24 x 32 array but I need to transfer data from columns in the first array to rows in the second.
I found an example (see attached file) where it's possible to extract a single column.
Is it possible to indexing the pointer in order to extract all columns?

BR

Extract column from 2D array.json (2.4 KB)

[E1cid]

Sure apply the map to each index position in a for loop.

let output = []
let depth = msg.payload[0].length
// take every column
for(let i = 0; i < depth; i++){
    let col = msg.payload.map((value) => value[i]);
    output.push(col);
}
msg.payload= output;
return msg;

[Geppy57]

Hi.
First of all, thanks for your answer.
I try to put the lines inside a function block, but the attached warning appears.
If I launch the program, the output is an empty array.
Something else to do / test to solve the question?
BR

[E1cid]

The warning is just a warning telling you that a function(the map) inside a loop referring to outside vars "may" cause an issue. In this case it will not, so can be ignored.

As to your result, seems strange as when i drop the function in your flow I get a result

[{"id":"e061ca3d.2e315","type":"inject","z":"bf9e1e33.030598","name":"Go","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":"","topic":"","payload":"1","payloadType":"str","x":190,"y":2100,"wires":[["203e0898.9e7e2"]]},{"id":"203e0898.9e7e2","type":"function","z":"bf9e1e33.030598","name":"fill numeric array (3 x 4)","func":"//var arr =[25,19,24,18,32,31,24,12,29,22,12,14]\nvar arr = [[1,2,3],[4,5,6],[7,8,9],[10,11,12]];\nmsg.payload = arr;\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","x":240,"y":2180,"wires":[["b6b6fec1.94c588","b8a4ae21.613328"]]},{"id":"b6b6fec1.94c588","type":"debug","z":"bf9e1e33.030598","name":"Array raw","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":490,"y":2140,"wires":[]},{"id":"b8a4ae21.613328","type":"function","z":"bf9e1e33.030598","name":"","func":"let output = []\nlet depth = msg.payload[0].length\n// take the third column\nfor(let i = 0; i < depth; i++){\n    let col = msg.payload.map((value) => value[i]);\n    output.push(col);\n}\nmsg.payload= output;\nreturn msg;\n","outputs":1,"noerr":0,"initialize":"","finalize":"","x":490,"y":2180,"wires":[["f46fae95.e94f9"]]},{"id":"f46fae95.e94f9","type":"debug","z":"bf9e1e33.030598","name":"desired column","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":730,"y":2180,"wires":[]}]

output

[[1,4,7,10],[2,5,8,11],[3,6,9,12]]

So it must be something you have added or removed, hard to tell any thing from the image you supplied.

[Geppy57]

Sorry.
It's my fault.
I put your sample into a different flow without formatting the input array.
Sorry for the inconvenience.
Thank you.