[Tutor] from string to variable name
hello, i have a string variable that contains a name that I want to use as a variablenameputting aside questions of why I would like to do that - i this possible at all?so I want to assign a value to a variable whos name is available only as a string to me. that variable does not exist yet in the local namespace.from: t = myvarto: myvar = 3is this possible? something like setattr?thanks for any insight you might have-frank ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] from string to variable name
frank h. wrote: hello, i have a string variable that contains a name that I want to use as a variablename putting aside questions of why I would like to do that - i this possible at all? so I want to assign a value to a variable whos name is available only as a string to me. that variable does not exist yet in the local namespace. from: t = myvar to: myvar = 3 is this possible? something like setattr? thanks for any insight you might have I think the point of dictionaries is to get this same basic functionality without polluting the namespaces. You won't let us ask you 'why' you want to do this, but I'll ask you: Why don't you want to use a dictionary? Do you want to know if it's _Possible_ just so you'll know, or do you actually want to use this for something? If you just want to know if it's possible, I believe it is. But consider: if you don't know the variable name until runtime, how are you going to refer to the variable later in your code? It would be, insofar as I can tell, useless to do this. -frank -Luke ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] from string to variable name
By string variable that contains a name that I want to use as a variablename do you mean something like this: myString = rotationalSpeed rotationalSpeed = 4500 ?? In Python a dictionary is an excellent solution to this problem. The only other way to accomplish this (to my knowledge) is in PHP (not trying to steer you away from Python, just giving some info): var myString = rotationalSpeed; $$myString = 4500; echo $rotationalSpeed; results in 4500. This is called variable variables in PHP and it can get hairy if done in a sloppy manner. I'm going to make the same recommendation that Luke did. Dictionaries are powerful structures. I recently wrote a Python script to parse an English dictionary file and build Markov models out of the words contained in the file (no, it wasn't for school, or work, or anything...I was just really, really bored). Rather than declaring an int to hold the frequency information for every letter, digram, and trigram possible (a total of 18,278 declarations), I used the letter, digram, or trigram as a key into a dictionary. Now I can do simple lookups by individual letters, digrams, or trigrams and see the frequency information without having to reference thousands of variables, and as an added side effect, only the letters, digrams, and trigrams that actually occur require storage. Jonathon Luke Paireepinart wrote: frank h. wrote: hello, i have a string variable that contains a name that I want to use as a variablename putting aside questions of why I would like to do that - i this possible at all? so I want to assign a value to a variable whos name is available only as a string to me. that variable does not exist yet in the local namespace. from: t = myvar to: myvar = 3 is this possible? something like setattr? thanks for any insight you might have I think the point of dictionaries is to get this same basic functionality without polluting the namespaces. You won't let us ask you 'why' you want to do this, but I'll ask you: Why don't you want to use a dictionary? Do you want to know if it's _Possible_ just so you'll know, or do you actually want to use this for something? If you just want to know if it's possible, I believe it is. But consider: if you don't know the variable name until runtime, how are you going to refer to the variable later in your code? It would be, insofar as I can tell, useless to do this. -frank -Luke ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] from string to variable name
On 10/5/06, frank h. [EMAIL PROTECTED] wrote: hello, i have a string variable that contains a name that I want to use as a variablename setattr() won't work because that's only for objects which have attributes. you're talking about creating a (global or local) variable. i will also recommend you use a dictionary too... it's flexible and powerful. but if you *have* to do it, to paraphrase jonathon's example: myString = 'rotationalSpeed' exec '%s = 4500' % myString print rotationalSpeed 4500 it's ugly but works. this example is more useful if you're planning on dynamically-generated lots of Python code to execute, not just a single assignment like this. good luck! -- wesley - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Core Python Programming, Prentice Hall, (c)2007,2001 http://corepython.com wesley.j.chun :: wescpy-at-gmail.com python training and technical consulting cyberweb.consulting : silicon valley, ca http://cyberwebconsulting.com ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
