Re: When should I use "parent=None" in __ini__ and "parent" in super()
Those are contradictory for what you are trying to accomplish unless it is a
Parent - Child relationship (MainWindow - Window):
When you super() an object, it enherits all the properties from its parent
object.
Source:
https://www.w3schools.com/python/python_inheritance.asp
If what you want is 2 windows, you can define 2 instances of both Classes and
run both at the end.
```
class User1(object):
def __init__(self, fname, age, parent=None):
self.fname = fname
self.age = int(age)
# Calling the return function that prints the details
self.return_user()
def return_user(self):
print(self.fname)
print(self.age)
class User2(object):
def __init__(self, lname, height, parent=None):
self.lname = lname
self.height = float(height)
self.return_user()
def return_user(self):
print(self.lname)
print(self.height, "CM")
print((self.height / 2.54), "IN")
User1("Hugh", 21)
User2("Janus", 175.26)
```
--
https://mail.python.org/mailman/listinfo/python-list
Re: How to make a variable's late binding crosses the module boundary?
ery...@gmail.com 在 2022年9月2日 星期五凌晨12:41:46 [UTC+8] 的信中寫道： > On 8/31/22, Jach Feng wrote: > > > > I found that using "from test import *" in test2.py makes test2's relation > > to "test" almost like the function's relation to the module where it is > > defined. You can refer to all the variables of the module > Note that in general, if __all__ doesn't exist to explicitly define > the contents of a star import, then it imports everything except names > that begin with an underscore. Thank you for pointing out these important difference:-) --Jach -- https://mail.python.org/mailman/listinfo/python-list
Re: Local variable definition in Python list comprehension
Dumb question. Your y is purely a function of x. So create an f(x) where you want your y. It probably can even be anonymous inline. I mean your return values of (x, y) would be (x, f(x)) ... On Thu, Sep 1, 2022, 5:04 PM Chris Angelico wrote: > On Fri, 2 Sept 2022 at 06:55, James Tsai wrote: > > > > 在 2022年9月1日星期四 UTC+2 18:34:36， 写道： > > > On 9/1/22, James Tsai wrote: > > > > > > > > I find it very useful if I am allowed to define new local variables > in a > > > > list comprehension. For example, I wish to have something like > > > > [(x, y) for x in range(10) for y := x ** 2 if x + y < 80], or > > > > [(x, y) for x in range(10) with y := x ** 2 if x + y < 80]. > > > > > > > > For now this functionality can be achieved by writing > > > > [(x, y) for x in range(10) for y in [x ** 2] if x + y < 80]. > > > You can assign a local variable in the `if` expression. For example: > > > > > > >>> [(x, y) for x in range(10) if x + (y := x**2) < 30] > > > [(0, 0), (1, 1), (2, 4), (3, 9), (4, 16)] > > > > Yeah this works great but like [(x, y) for x in range(10) for y in > [x**2]] I written before, is kind of a hack. And if initially I do not need > an "if" condition in the list comprehension, this becomes less convenient. > I still can write > > >>> [(x, y) for x in range(10) if (y := x**2) or True] > > > > But I wonder if Python could have a specific syntax to support this. > > > > But why would you need to assign to y in that example? If you're using > it more than once, you can use :=, and if you aren't, you don't need > to. But do be aware that := does not create a comprehension-local name > binding, but a nonlocal instead. > > > No but very often when I have written a neat list/dict/set > comprehension, I find it very necessary > > to define local variable(s) to make it more clear and concise. Otherwise > I have to break it down > > to several incrementally indented lines of for loops, if statements, and > variable assignments, > > which I think look less nice. > > Well, if it's outgrown a list comp, write it on multiple lines. Like I > said, not everything has to be a one-liner. > > ChrisA > -- > https://mail.python.org/mailman/listinfo/python-list > -- https://mail.python.org/mailman/listinfo/python-list
Re: Local variable definition in Python list comprehension
On 02Sep2022 07:01, Chris Angelico wrote: >On Fri, 2 Sept 2022 at 06:55, James Tsai wrote: >> No but very often when I have written a neat list/dict/set >> comprehension, I find it very necessary >> to define local variable(s) to make it more clear and concise. Otherwise I >> have to break it down >> to several incrementally indented lines of for loops, if statements, and >> variable assignments, >> which I think look less nice. > >Well, if it's outgrown a list comp, write it on multiple lines. Like I >said, not everything has to be a one-liner. True, but a comprehension can be more expressive than a less "functional" expression (series of statements). James, can you provide (a) a real world example where you needed to write a series of statements or loops and (b) a corresponding example of how you would have preferred to have written that code, possibly inventing some syntax or misusing ":=" as if it workeed they way you'd like it to work? Cheers, Cameron Simpson -- https://mail.python.org/mailman/listinfo/python-list
Re: Local variable definition in Python list comprehension
On 2022-09-01 13:33:16 -0700, James Tsai wrote: > 在 2022年9月1日星期四 UTC+2 18:34:36， 写道： > > On 9/1/22, James Tsai wrote: > > > > > > I find it very useful if I am allowed to define new local variables in a > > > list comprehension. For example, I wish to have something like > > > [(x, y) for x in range(10) for y := x ** 2 if x + y < 80], or > > > [(x, y) for x in range(10) with y := x ** 2 if x + y < 80]. > > > > > > For now this functionality can be achieved by writing > > > [(x, y) for x in range(10) for y in [x ** 2] if x + y < 80]. > > You can assign a local variable in the `if` expression. For example: > > > > >>> [(x, y) for x in range(10) if x + (y := x**2) < 30] > > [(0, 0), (1, 1), (2, 4), (3, 9), (4, 16)] > > Yeah this works great but like [(x, y) for x in range(10) for y in > [x**2]] I written before, is kind of a hack. And if initially I do not > need an "if" condition in the list comprehension, this becomes less > convenient. I still can write > >>> [(x, y) for x in range(10) if (y := x**2) or True] In that case [(x, x**2) for x in range(10)] seems to be somewhat more readable. I would also say that [(x, x**2) for x in range(10) if x + x**2 < 80] doesn't really seem worse than any of the variants with y in it. (Yes, I get that your real duplicated expression is probably a bit more complex than `x**2`, but by the time a temporary variable really improves readability it's probably a good time to split that across multiple lines, too.) hp -- _ | Peter J. Holzer| Story must make more sense than reality. |_|_) || | | | h...@hjp.at |-- Charles Stross, "Creative writing __/ | http://www.hjp.at/ | challenge!" signature.asc Description: PGP signature -- https://mail.python.org/mailman/listinfo/python-list
Re: Local variable definition in Python list comprehension
On Fri, 2 Sept 2022 at 06:55, James Tsai wrote: > > 在 2022年9月1日星期四 UTC+2 18:34:36， 写道： > > On 9/1/22, James Tsai wrote: > > > > > > I find it very useful if I am allowed to define new local variables in a > > > list comprehension. For example, I wish to have something like > > > [(x, y) for x in range(10) for y := x ** 2 if x + y < 80], or > > > [(x, y) for x in range(10) with y := x ** 2 if x + y < 80]. > > > > > > For now this functionality can be achieved by writing > > > [(x, y) for x in range(10) for y in [x ** 2] if x + y < 80]. > > You can assign a local variable in the `if` expression. For example: > > > > >>> [(x, y) for x in range(10) if x + (y := x**2) < 30] > > [(0, 0), (1, 1), (2, 4), (3, 9), (4, 16)] > > Yeah this works great but like [(x, y) for x in range(10) for y in [x**2]] I > written before, is kind of a hack. And if initially I do not need an "if" > condition in the list comprehension, this becomes less convenient. I still > can write > >>> [(x, y) for x in range(10) if (y := x**2) or True] > > But I wonder if Python could have a specific syntax to support this. > But why would you need to assign to y in that example? If you're using it more than once, you can use :=, and if you aren't, you don't need to. But do be aware that := does not create a comprehension-local name binding, but a nonlocal instead. > No but very often when I have written a neat list/dict/set comprehension, I > find it very necessary > to define local variable(s) to make it more clear and concise. Otherwise I > have to break it down > to several incrementally indented lines of for loops, if statements, and > variable assignments, > which I think look less nice. Well, if it's outgrown a list comp, write it on multiple lines. Like I said, not everything has to be a one-liner. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: Local variable definition in Python list comprehension
在 2022年9月1日星期四 UTC+2 18:16:03， 写道： > On Fri, 2 Sept 2022 at 02:10, James Tsai wrote: > > > > Hello, > > > > I find it very useful if I am allowed to define new local variables in a > > list comprehension. For example, I wish to have something like > > [(x, y) for x in range(10) for y := x ** 2 if x + y < 80], or > > [(x, y) for x in range(10) with y := x ** 2 if x + y < 80]. > > > > For now this functionality can be achieved by writing > > [(x, y) for x in range(10) for y in [x ** 2] if x + y < 80]. > > > > Is it worthwhile to add a new feature like this in Python? If so, how can I > > propose this to PEP? > Not everything has to be a one-liner. > > ChrisA No but very often when I have written a neat list/dict/set comprehension, I find it very necessary to define local variable(s) to make it more clear and concise. Otherwise I have to break it down to several incrementally indented lines of for loops, if statements, and variable assignments, which I think look less nice. -- https://mail.python.org/mailman/listinfo/python-list
Re: Local variable definition in Python list comprehension
在 2022年9月1日星期四 UTC+2 18:34:36， 写道： > On 9/1/22, James Tsai wrote: > > > > I find it very useful if I am allowed to define new local variables in a > > list comprehension. For example, I wish to have something like > > [(x, y) for x in range(10) for y := x ** 2 if x + y < 80], or > > [(x, y) for x in range(10) with y := x ** 2 if x + y < 80]. > > > > For now this functionality can be achieved by writing > > [(x, y) for x in range(10) for y in [x ** 2] if x + y < 80]. > You can assign a local variable in the `if` expression. For example: > > >>> [(x, y) for x in range(10) if x + (y := x**2) < 30] > [(0, 0), (1, 1), (2, 4), (3, 9), (4, 16)] Yeah this works great but like [(x, y) for x in range(10) for y in [x**2]] I written before, is kind of a hack. And if initially I do not need an "if" condition in the list comprehension, this becomes less convenient. I still can write >>> [(x, y) for x in range(10) if (y := x**2) or True] But I wonder if Python could have a specific syntax to support this. -- https://mail.python.org/mailman/listinfo/python-list
Re: Local variable definition in Python list comprehension
在 2022年9月1日星期四 UTC+2 16:15:17， 写道： > James Tsai writes: > > > I find it very useful if I am allowed to define new local variables in > > a list comprehension. For example, I wish to have something like > > [(x, y) for x in range(10) for y := x ** 2 if x + y < 80], or > > [(x, y) for x in range(10) with y := x ** 2 if x + y < 80]. > > > > For now this functionality can be achieved by writing > > [(x, y) for x in range(10) for y in [x ** 2] if x + y < 80]. > x and y are, to a first approximation, new local variables defined in a > list comprehension. I think you need to restate what it is you want. > > Is it worthwhile to add a new feature like this in Python? If so, how > > can I propose this to PEP? > To make any sort of case you'd need to give an example that does not > have a clearer way to write it already. Your working version is, to me, > clearer that the ones you want to be able to write. > > -- > Ben. By local variable definition I mean binding a variable to a single value, so it doesn't include giving an iterable that a variable can take values iteratively, e.g. 'for x in range(10)'. Does it not worth introducing a specific syntax to do this, instead of creating a new list ad hoc to define the variable like 'for y in [1]'? -- https://mail.python.org/mailman/listinfo/python-list
Re: How to make a variable's late binding crosses the module boundary?
On 8/31/22, Jach Feng wrote: > > I found that using "from test import *" in test2.py makes test2's relation > to "test" almost like the function's relation to the module where it is > defined. You can refer to all the variables of the module Note that in general, if __all__ doesn't exist to explicitly define the contents of a star import, then it imports everything except names that begin with an underscore. -- https://mail.python.org/mailman/listinfo/python-list
Re: Local variable definition in Python list comprehension
On 9/1/22, James Tsai wrote: > > I find it very useful if I am allowed to define new local variables in a > list comprehension. For example, I wish to have something like > [(x, y) for x in range(10) for y := x ** 2 if x + y < 80], or > [(x, y) for x in range(10) with y := x ** 2 if x + y < 80]. > > For now this functionality can be achieved by writing > [(x, y) for x in range(10) for y in [x ** 2] if x + y < 80]. You can assign a local variable in the `if` expression. For example: >>> [(x, y) for x in range(10) if x + (y := x**2) < 30] [(0, 0), (1, 1), (2, 4), (3, 9), (4, 16)] -- https://mail.python.org/mailman/listinfo/python-list
Re: Local variable definition in Python list comprehension
On Fri, 2 Sept 2022 at 02:10, James Tsai wrote: > > Hello, > > I find it very useful if I am allowed to define new local variables in a list > comprehension. For example, I wish to have something like > [(x, y) for x in range(10) for y := x ** 2 if x + y < 80], or > [(x, y) for x in range(10) with y := x ** 2 if x + y < 80]. > > For now this functionality can be achieved by writing > [(x, y) for x in range(10) for y in [x ** 2] if x + y < 80]. > > Is it worthwhile to add a new feature like this in Python? If so, how can I > propose this to PEP? Not everything has to be a one-liner. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: Local variable definition in Python list comprehension
James Tsai writes: > I find it very useful if I am allowed to define new local variables in > a list comprehension. For example, I wish to have something like > [(x, y) for x in range(10) for y := x ** 2 if x + y < 80], or > [(x, y) for x in range(10) with y := x ** 2 if x + y < 80]. > > For now this functionality can be achieved by writing > [(x, y) for x in range(10) for y in [x ** 2] if x + y < 80]. x and y are, to a first approximation, new local variables defined in a list comprehension. I think you need to restate what it is you want. > Is it worthwhile to add a new feature like this in Python? If so, how > can I propose this to PEP? To make any sort of case you'd need to give an example that does not have a clearer way to write it already. Your working version is, to me, clearer that the ones you want to be able to write. -- Ben. -- https://mail.python.org/mailman/listinfo/python-list
Re: How to make a variable's late binding crosses the module boundary?
Mark Bourne 在 2022年9月1日 星期四凌晨2:43:40 [UTC+8] 的信中寫道： > Jach Feng wrote: > > Mark Bourne 在 2022年8月29日 星期一下午6:40:59 [UTC+8] 的信中寫道： > >> Jach Feng wrote: > >>> Chris Angelico 在 2022年8月29日 星期一下午1:58:58 [UTC+8] 的信中寫道： > On Mon, 29 Aug 2022 at 15:54, Jach Feng wrote: > > > > Richard Damon 在 2022年8月29日 星期一上午10:47:08 [UTC+8] 的信中寫道： > >> On 8/27/22 7:42 AM, Mark Bourne wrote: > >>> Jach Feng wrote: > I have two files: test.py and test2.py > --test.py-- > x = 2 > def foo(): > print(x) > foo() > > x = 3 > foo() > > --test2.py-- > from test import * > x = 4 > foo() > > - > Run test.py under Winows8.1, I get the expected result: > e:\MyDocument>py test.py > 2 > 3 > > But when run test2.py, the result is not my expected 2,3,4:-( > e:\MyDocument>py test2.py > 2 > 3 > 3 > > What to do? > >>> > >>> `from test import *` does not link the names in `test2` to those in > >>> `test`. It just binds objects bound to names in `test` to the same > >>> names in `test2`. A bit like doing: > >>> > >>> import test > >>> x = test.x > >>> foo = test.foo > >>> del test > >>> > >>> Subsequently assigning a different object to `x` in one module does > >>> not affect the object assigned to `x` in the other module. So `x = 4` > >>> in `test2.py` does not affect the object assigned to `x` in `test.py` > >>> - that's still `3`. If you want to do that, you need to import `test` > >>> and assign to `test.x`, for example: > >>> > >>> import test > >>> test.x = 4 > >>> test.foo() > >>> > >> Yes, fundamental issue is that the statement > >> > >> from x import y > >> > >> makes a binding in this module to the object CURRECTLY bound to x.y to > >> the name y, but if x.y gets rebound, this module does not track the > >> changes. > >> > >> You can mutate the object x.y and see the changes, but not rebind it. > >> > >> If you need to see rebindings, you can't use the "from x import y" > >> form, > >> or at a minimum do it as: > >> > >> > >> import x > >> > >> from x import y > >> > >> then later to get rebindings to x.y do a > >> > >> y = x.y > >> > >> to rebind to the current x.y object. > >> > >> -- > >> Richard Damon > > Yes, an extra "import x" will solve my problem too! Sometimes I am > > wondering why "from x import y" hides x? hum...can't figure out the > > reason:-) > > > "from x import y" doesn't hide x - it just grabs y. Python does what > you tell it to. :) > > ChrisA > >>> But I had heard people say that "from x import y" did import the whole x > >>> module into memory, just as "import x" did, not "grabs y" only. Is this > >>> correct? > >> `from x import y` does import the whole module x into memory, and adds > >> it to `sys.modules`. But it only binds the name `y` in the namespace of > >> module doing the import (and it binds it to the value of `x.y` at the > >> time the import is done - it doesn't magically keep them in sync if one > >> or the other is later reassigned). > >> > >> The point about the whole module being imported is that you don't save > >> any memory by using `from x import y` to avoid importing some very large > >> object `z` from `x`. Those other large objects might be needed by > >> functions which have been imported (e.g. your `foo` function still needs > >> `x` even if you haven't imported `x` - so it still needs to be loaded > >> into memory) or might be imported and used by other modules importing > >> `x`, so they still have to be loaded when any part of `x` is imported - > >> they just don't have to be bound to names in the importing module's > >> namespace. > >> > >> As Richard mentioned, if `x.y` is a mutable object (such as a list) you > >> can still mutate that object (e.g. add/remove items) and those changes > >> will be seen in both modules. That's because both are still bound to > >> the same object and you're mutating that existing object. If you assign > >> a new list to either, that won't be seen by the other. > >> > >> -- > >> Mark. > > When using dot notation to change variable, no matter if 'x.y' is a mutable > > or immutable object, the change > > will be seen in both modules except those early bindings. > > > > --Jach > Yes, sorry, I'd used `x.y` as a way of referring to the variable `y` in > module `x` as opposed to `y` in the current module. It doesn't help > that I added the second paragraph and didn't notice that the third was > then out of context. > > If you use `import x` and
Local variable definition in Python list comprehension
Hello, I find it very useful if I am allowed to define new local variables in a list comprehension. For example, I wish to have something like [(x, y) for x in range(10) for y := x ** 2 if x + y < 80], or [(x, y) for x in range(10) with y := x ** 2 if x + y < 80]. For now this functionality can be achieved by writing [(x, y) for x in range(10) for y in [x ** 2] if x + y < 80]. Is it worthwhile to add a new feature like this in Python? If so, how can I propose this to PEP? -- https://mail.python.org/mailman/listinfo/python-list
[Python-announce] ANN: pvlib-0.9.2 released
Dear Pythonistas and solar power enthusiasts, The maintainers are happy to announce a new release of pvlib python: software for simulating performance of photovoltaic solar energy systems. *See what's new for v0.9.2:* ** *https://pvlib-python.readthedocs.io/en/stable/whatsnew.html *Releases are available from PyPI and the conda-forge channel:* * https://pypi.org/project/pvlib/ * https://anaconda.org/conda-forge/pvlib * https://anaconda.org/conda-forge/pvlib-python *Note: you can now install from conda-forge using either "pvlib" or "pvlib-python"* *Read the Documentation:* * https://pvlib-python.readthedocs.io/en/stable/index.html *Report issues & contribute:* * https://github.com/pvlib/pvlib-python *Highlights:* * Albedo can be entered as a column in weather DataFrame when running a model chain. This can be used to enter a time series instead of just monthly values. * A new function calc_surface_orientation() returns tracker surface tilt and azimuth when given tracker rotation and axis tilt. * There's a new example in the gallery to calculate backside irradiance using pvfactors. * Dropped support for Python-3.6 and increased required pandas to v0.25.0 * A new build system that conforms to PEP 517 & PEP518 * There were several new contributors. *Thank you for using pvlib python!* -- Mark Mikofski, PhD (2005) *Fiat Lux* ___ Python-announce-list mailing list -- python-announce-list@python.org To unsubscribe send an email to python-announce-list-le...@python.org https://mail.python.org/mailman3/lists/python-announce-list.python.org/ Member address: arch...@mail-archive.com
