[Tutor] Assessing local variable outside function
Hello, Could i use a variable defined in a function in another function? I have now: def DatasetToSubset(file, LatUpbound, LatLowBound, LonUpBound, LonLowBound): nc=netCDF4.Dataset(file) lats=nc.variables['lat'][:]; lons=nc.variables['lon'][:] latselect=np.logical_and(lats > LatLowBound, lats < LatUpBound) lonselect=np.logical_and(lon > LonLowBound, lon < LonUpBound) data=nc.variables['Runoff'][1000, latselect, lonselect] return data; return latselect; return lonselect So, i want to use latselect and lonselect in a different function where i interpolate for the subsetted area. Nils ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] comp.lang.python on gmane
On Thu, Oct 27, 2016, at 20:40, Jim Byrnes wrote: > Is comp.lang.python available on gmane? > > I've googled and found references to it being on gmane but I can't find > it there. I'd like to use gmane because Comcast doesn't do usenet > anymore. I don't know about the current viability of gmane in general, but it's called "gmane.comp.python.general" on gmane. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Assessing local variable outside function
On 28/10/16 02:38, nils wagenaar wrote: > Hello, > > > Could i use a variable defined in a function in another function? By returning it to the caller. > def DatasetToSubset(file, LatUpbound, LatLowBound, LonUpBound, LonLowBound): > nc=netCDF4.Dataset(file) > lats=nc.variables['lat'][:]; lons=nc.variables['lon'][:] > latselect=np.logical_and(lats > LatLowBound, lats < LatUpBound) > lonselect=np.logical_and(lon > LonLowBound, lon < LonUpBound) > data=nc.variables['Runoff'][1000, latselect, lonselect] > return data; return latselect; return lonselect The syntax for return is return value And you can only have one return on the line. But value can be a tuple so to do what you want: return data, latselect, lonselect And your caller can use something like dat,lat,lon = DatasetToSubset() The other way to do it is to create a class containing all the functions that use the same data and put the shared variables as instance attributes. class LatAndLon:# think of a better name! :-) def __init__(self, file, lat=None, lon=None): self.file = file self.lat = lat self.lon = lon def datasetToSubset(self, .): nc = ... ... self.lat = ... self.lon = ... self.data = ... def another_function(self,...): if self.lat == 42: self.process(data) elis self.lon > 66: self.format() #etc... Then create an instance and call the methods as needed vals = LatAndLon() vals.datasetToSubset() vals.another_function() That way the data stays outside the global namespace but the functions that use it can all see it. You will likely find that this greatly reduces the number of params you need to pass to each function since you set them up once, when you create the instance, and don't need to keep passing them into the functions. This makes the code easier to write and maintain. HTH -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.amazon.com/author/alan_gauld Follow my photo-blog on Flickr at: http://www.flickr.com/photos/alangauldphotos ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Assessing local variable outside function
nils wagenaar wrote: > Hello, > > > Could i use a variable defined in a function in another function? > > I have now: > > > def DatasetToSubset(file, LatUpbound, LatLowBound, LonUpBound, > LonLowBound): > nc=netCDF4.Dataset(file) > lats=nc.variables['lat'][:]; lons=nc.variables['lon'][:] > latselect=np.logical_and(lats > LatLowBound, lats < LatUpBound) > lonselect=np.logical_and(lon > LonLowBound, lon < LonUpBound) > data=nc.variables['Runoff'][1000, latselect, lonselect] > return data; return latselect; return lonselect It doesn't help that you put all return statements on the same line, only the first return data is executed; the other two are unreachable code. > So, i want to use latselect and lonselect in a different function where i > interpolate for the subsetted area. In Python while you can return only one value you can easily combine multiple values into one tuple. Instead of > return data; return latselect; return lonselect write return data, latselect, lonselect When you call the function you can either access the parts of the tuple with their respective index result = DatasetToSubset(...) lat = result[1] or use a language feature called "unpacking" to break the tuple into the individual values: data, lat, lon = DatasetToSubset(...) ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Assessing local variable outside function
Alan Gauld via Tutor writes: > On 28/10/16 02:38, nils wagenaar wrote: > > Could i use a variable defined in a function in another function? My answer would be: You can't because Python variables don't exist outside their namespace. You can make the object available in various ways, but not the variable. > By returning it to the caller. That's somewhat misleading. Returning the *object* would not grant access to the local *variable*. Nils, it's important to realise that a variable in Python is not tractable: you can't hand them around, you can't access the name itself. A Python variable exists only in its namespace, and can't move. The variable is (at any given point) bound to an object; you can get *other* variables bound to the same object by explicitly doing that. Alan suggests one way. Whether that meets your request to “use a variable defined in a function in another function” will have to wait for you to check how the Python data model actually works. Does that answer it, or do you need something different? -- \ “Dare to be naïve.” —Richard Buckminster Fuller, personal motto | `\ | _o__) | Ben Finney ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] comp.lang.python on gmane
On 10/27/2016 09:54 PM, Random832 wrote: On Thu, Oct 27, 2016, at 20:40, Jim Byrnes wrote: Is comp.lang.python available on gmane? I've googled and found references to it being on gmane but I can't find it there. I'd like to use gmane because Comcast doesn't do usenet anymore. I don't know about the current viability of gmane in general, but it's called "gmane.comp.python.general" on gmane. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor That worked. Not sure how I over looked it the other times I was trying to subscribe. Thanks much. Regards, Jim ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] comp.lang.python on gmane
>>> >>> Is comp.lang.python available on gmane? >>> >>> I've googled and found references to it being on gmane but I can't find >>> it there. I'd like to use gmane because Comcast doesn't do usenet >>> anymore. >> >> >> I don't know about the current viability of gmane in general, but it's >> called "gmane.comp.python.general" on gmane. Ah, excellent! Can someone correct the link on the wiki? https://wiki.python.org/moin/CompLangPython. (I'm away from a keyboard at the moment.) ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] comp.lang.python on gmane
Ah. The wiki link does point to the expected place after all. I think, then, that the initial assessment is accurate, that Gmane is still recovering their archives, and that eventually the link will work again. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Assessing local variable outside function
Thank you all! It is clear now:) Verstuurd vanaf mijn iPhone > Op 28 okt. 2016 om 19:31 heeft Ben Finney het > volgende geschreven: > > Alan Gauld via Tutor writes: > >>> On 28/10/16 02:38, nils wagenaar wrote: >>> Could i use a variable defined in a function in another function? > > My answer would be: You can't because Python variables don't exist > outside their namespace. > > You can make the object available in various ways, but not the variable. > >> By returning it to the caller. > > That's somewhat misleading. Returning the *object* would not grant > access to the local *variable*. > > Nils, it's important to realise that a variable in Python is not > tractable: you can't hand them around, you can't access the name itself. > A Python variable exists only in its namespace, and can't move. > > The variable is (at any given point) bound to an object; you can get > *other* variables bound to the same object by explicitly doing that. > Alan suggests one way. > > Whether that meets your request to “use a variable defined in a function > in another function” will have to wait for you to check how the Python > data model actually works. Does that answer it, or do you need something > different? > > -- > \ “Dare to be naïve.” —Richard Buckminster Fuller, personal motto | > `\ | > _o__) | > Ben Finney > > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > https://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] run local script on a remote machine
If you're trying to do remote command execution, you should forget about rolling your own, and use a well-established RPC solution. I can recommend either of pyro or rpyc: https://pypi.python.org/pypi/Pyro4 https://pypi.python.org/pypi/rpyc If you need a standard library solution, you can try: https://docs.python.org/3/library/xmlrpc.html -- Steve ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
