"PMVector sum" is extremely slow, and two more issues

[Atharva Khare]

Hey everyone,

I found three issues in the library, they are written below sorted by their severity. Please go through them and suggest better fixes, if any.

1. "PMVector sum" - Here is the comparison with array:

a := ((1 to: 5000) collect: [ :i | i ]) asPMVector.
a sum. "Best of 10 runs: 568ms"

b := ((1 to: 25000000) collect: [ :i | i ]).
b sum. "Worst of 10 runs: 551ms"

This means that PMVector sum is at least 5,000 times slower than Collection sum.

Possible fix: Don't override sum method. Is there any specific reason to override?

2. PMVector > < operators modify in-place:

x := #(1 2.5 3 4) asPMVector.
x > 2.
x. "==> a PMVector(false true true true)"

I have created a PR for it, here: https://github.com/PolyMathOrg/PolyMath/pull/123
Should additional operators like >= and <= be added in similar fashion as well?

3. PMStandardScaler fails when scale = 0 - happens when all elements in a column are equal. Possible fix: add a "handleZeroScale" method which changes scale to 1 when it is 0.
Question: Should this method be added in PMDataTransformer? If we add more scalers in future, all would need this message.

[Atharva Khare]

Forgot to link the issues:

1. PMVector sum - https://github.com/PolyMathOrg/PolyMath/issues/125

2. PMVector > < operators - https://github.com/PolyMathOrg/PolyMath/issues/122

3. Standardscalar scale=0 - https://github.com/PolyMathOrg/PolyMath/issues/124

[Serge Stinckwich]

On Sun, May 26, 2019 at 1:29 PM Atharva Khare <kharea...@gmail.com> wrote:

Hey everyone,

Dear Atharva,

 

I found three issues in the library, they are written below sorted by their severity. Please go through them and suggest better fixes, if any.

1. "PMVector sum" - Here is the comparison with array:

a := ((1 to: 5000) collect: [ :i | i ]) asPMVector.
a sum. "Best of 10 runs: 568ms"

b := ((1 to: 25000000) collect: [ :i | i ]).
b sum. "Worst of 10 runs: 551ms"

This means that PMVector sum is at least 5,000 times slower than Collection sum.

Possible fix: Don't override sum method. Is there any specific reason to override?

I try to remove PMVector>>sum and it runs much faster.

All the tests are green. I agree to remove this method.

Thank you for your commitment to PolyMath.

--

Serge Stinckwic

h

Int. Research Unit

 on Modelling/Simulation of Complex Systems (UMMISCO)

Sorbonne University

 (SU)

French National Research Institute for Sustainable Development (IRD)

U

niversity of Yaoundé I, Cameroon

"Programs must be written for people to read, and only incidentally for machines to execute." https://twitter.com/SergeStinckwich