[issue46199] Calculation influenced by print

[Mark Dickinson]

Mark Dickinson  added the comment:

When you do:

FINUB = np.empty(len(close))
FINLB = np.empty(len(close))

you're creating two *uninitialised* arrays of values. (See the NumPy 
documentation at 
https://numpy.org/doc/stable/reference/generated/numpy.empty.html.)

When you then do 

FINUB[i] = UB[i] if UB[i] < FINUB[i-1] \
and close[i-1] > FINUB[i] else FINUB[i-1]

on the first iteration of the loop (i = 1), you make use of the (undefined) 
value in FINUB[0] to compute FINUB[1].

In other words, this is a bug in your code, rather than in Python or NumPy.

--
nosy: +mark.dickinson
resolution:  -> not a bug
stage:  -> resolved
status: open -> closed

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue46199] Calculation influenced by print

[Steven D'Aprano]

Steven D'Aprano  added the comment:

Please try to provide a minimal reproducible example:

https://stackoverflow.com/help/minimal-reproducible-example

http://sscce.org/

At the very least, you need to provide three pieces of information:

1. What you tried.
2. What you expected to happen (and why, if it isn't obvious).
3. What actually happened instead.


Ideally you should be able to get your example down to using one or two values, 
not three lists with 30 values each (90 values).

--
nosy: +steven.daprano

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue46199] Calculation influenced by print

[Eric V. Smith]

Eric V. Smith  added the comment:

This is likely not a bug in python. You might have better luck asking on a 
numpy support list.

That said, what results do you get, and what do you expect to get? We don't 
know what error you're seeing.

You might replace:
print("LB: ", LB)

with:
str(LB)

and see what happens. That's the only operation that's called on LB when you're 
printing.

--
nosy: +eric.smith

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue46199] Calculation influenced by print

[wby78826]

New submission from wby78826 :

(Could be a numpy bug)
##Just run the script, then uncomment Line 14 and run again
The result of "supertrend" is different, depending on whether I print "LB" 
first or not.
If I don't print it first, the result is wrong.

It also does'nt matter if I print it to stdout or stderr, it only works this 
way.

(sry if I did something wrong)

--
components: Windows
files: supertrend.py
messages: 409343
nosy: paul.moore, steve.dower, tim.golden, wby78826, zach.ware
priority: normal
severity: normal
status: open
title: Calculation influenced by print
type: behavior
versions: Python 3.9
Added file: https://bugs.python.org/file50527/supertrend.py

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com