Simple statistics question

[Ingo Dahn]

According to http://doc.sagemath.org/html/en/reference/stats/sage/stats/basic_stats.html

the following should work (and it used to):

data = [random() for i in [1 .. 20]]

std(data)

But it gives

AttributeError: 'float' object has no attribute 'sqrt'

Any hints?

[Harald Schilly]

Well, I can't find that example, or a similar one. I don't know if this is a bug or it just happened to work.

However, you can create random vectors in Sage, then it all fits well together:

data = random_vector(RR, 20)
std(data)

Regards, Harald

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[William Stein]

On Tue, Feb 11, 2020 at 9:33 AM Harald Schilly <h...@sagemath.com> wrote:
>
> Well, I can't find that example, or a similar one. I don't know if this is a bug or it just happened to work.

Ingo -- thanks for finding this. It is definitely a bug. It is a bug
that Frédéric Chapoton introduced into a recent version of Sage when
doing some automated cleanup of the source code:

https://github.com/sagemath/sage/commit/c946256d9a2dce49beaef6b28c6e36df9a0a2b4b#diff-d0fae2d422c3c6f113110121d9faa9a6R219

I've cc'd Frédéric so he can fix this.

I guess this is one of the drawbacks of automated style suggestion
software; it suggests changes that look good at first glance, but can
break code. Your example should be a doctest.

This is a workaround in the current version of Sage:

sage: std([RR(random()) for i in [1 .. 20]])
0.291469277800344

However, it is slower. Harald's suggestion to convert to a numpy
array would be faster.

In case anybody is curious all these basic stats functions were first
written by Andrew Hou (https://github.com/amhou) as a univ. of
Washington undergrad student project... They really do have value
because they work on any number types (e.g., symbolics, etc.).

> To view this discussion on the web visit https://groups.google.com/d/msgid/cocalc/CA%2BCu88QiKa%2B1tnaUvrfYgM6jzsZEzZ5gsQ6X25jPjvo%3DCFv8-Q%40mail.gmail.com.



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Best Regards,
William Stein

CEO, SageMath, Inc.

[Ingo Dahn]

I have another case of "float has no attribute...":

show(plot(factorial(x),(x,1,5)))

which used to work previously.

[Samuel Lelièvre]

Le jeudi 13 février 2020 22:31:14 UTC+1, Ingo Dahn a écrit :

I have another case of "float has no attribute...":

show(plot(factorial(x),(x,1,5)))

which used to work previously.

That one is solved at

- Sage Trac ticket 26749

  Let `factorial` accept float arguments

  https://trac.sagemath.org/ticket/26749

pending positive review and merging in the next Sage version.

A similar solution should work for `sqrt`.

[Samuel Lelièvre]

Note: this is fixed in

- Sage Trac ticket 29184

  fix for some basic stats function

  https://trac.sagemath.org/ticket/29184

which was merged in Sage 9.1.beta5,

see the release announcement from

less than an hour ago:

https://groups.google.com/d/topic/sage-release/_-Bbut2E_-g/discussion

Samuel

2020-02-11 19:37:05 UTC+1, William Stein:

[Ingo Dahn]

? It is still not working in Cocalc nor SageCell. Please, give a note when it does.

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