I’ve the below Python code: def initial_trend(series, slen): sum = 0.0 for i in range(slen): sum += float(series[i+slen] - series[i]) / slen return sum / slen That is converted to the below Rust code: fn initial_trend(series: &[i32], slen: usize) -> f32 { series[..slen].it…

If you want a “functional” approach, you can also do initial_trend(series, slen) = mapreduce(+, zip(series[1:slen], series[slen+1:2*slen])) do (a, b) (b - a) / slen end / slen If you care performance a bit then, function initial_trend(series, slen) x = @view series[1:slen] …

[image] Tamas_Papp: (series[slen:end] .- series[1:slen]) ./ 2 for this I got: DimensionMismatch("arrays could not be broadcast to a common size")

Just think about it for a sec. Eg imagine that series has 10 elements and slen is 2.

[image] Tamas_Papp: y = map((a, b) → b - a / 2, series[1:slen], series[slen:end]) for this also,I got the same: y = map((a, b) -> (b - a) / 2, series[1:12], series[12+1:end]) DimensionMismatch("dimensions must match")

Of course, it’s the same problem.

Maybe: function initial_trend(series, slen) sum = 0.0 for i in 1:slen sum += series[i+slen]-series[i] end return sum/slen end I worked from the python and removed what I suspect is a redundant /slen (it is being done both in the loop and outside the loop). P.S. I’m assuming tha…

Thanks, actually the other slen is required, not extra sum += (series[i+slen]-series[i]) / slen Your code with returning the slen gave me the correct output, so now how can I covert this Julia code to functional format using Iter

[image] Tamas_Papp: imagine that series has 10 elements and slen is 2. So, how can we enforce it to work based on the shortest array, so for 10 and 2, it will take only the first 2 elements from the array of 10

[image] hasanOryx: it will take only the first 2 elements from the array of 10 zip does that. did you read my very first reply? nope it does not work that way. I would just calculate indexes to match in length, like @dmolina suggests, and maybe use @view.

In that case, I would suggest: y = map((a, b) -> (b - a) / 2, series[1:slen-1], series[slen+1:2*slen]) Be careful with indexes, julia series[1:n] includes n index, while Python does not. Edit: Sorry, it was missing a parenthesis.

[image] dmolina: y = map((a, b) → (b - a) / 2, series[1:slen], series[slen+1:slen]) I got: DimensionMismatch("dimensions must match") Iter b is bigger than iter a so it fails, how can I ask it to take the first x elements in iter b where x is the length(a)

Help fo working with Iters

New to Julia

dmolina October 10, 2019, 3:20pm 15

I do not think so, zips stop when one of them finish before the other one, but for some reason this check is only done in a for loop, not inside a map or the collect function.

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Help fo working with Iters

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