accessing PART of a file name based on user input to a function--Python

Question

I'm a newb trying to figure out how to accomplish the following:

I have dicts named after users in the following format:

<user>_hx

I want to access them with a function like so:

def foo(user, other_stuff):
  user_hx[key]

......etc.

I attempted to access with % as follows:

def foo(user, other_stuff):
  %r_hx %user[key]

but for obvious reasons I know that can't work.

Adivce?

how about eval(user+'_hx'), although eval is not recommended — daydreamer
– daydreamer, Commented Jul 26, 2012 at 22:29
yeah Im missing something here... its not clear what you are trying to do... do you mean "%s_hx"%user[key] ? you open a file with open(filename,fileMode) — Joran Beasley
– Joran Beasley, Commented Jul 26, 2012 at 22:29

Isaac · Accepted Answer · 2012-07-26 22:31:48Z

1

What I think you are asking is how to access a variable based on a string representing its name. Python makes this quite easy:

globals()['%s_hx' % user]

will give you the variable <user>_hx, so you just want

globals()['%s_hx' % user][key]

(I'm not sure whether you should be using globals() or locals(); it will depend on how your variables are defined and where you are trying to access them from)

That said, there is probably an easier/cleaner way to do whatever you are doing. For instance, have you considered putting all these dictionaries in a 'master' dictionary so that you can pass them around, as well as just access them

answered Jul 26, 2012 at 22:31

Isaac

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2 Comments

Daniel DiPaolo Over a year ago

Yeah, I would definitely not recommend doing this ever. It's marginally better than eval but still worse than just using a dict of dicts which is what I'm guessing would be the right solution here.

Keith Over a year ago

There's no need to do this. Just put the dictionaries inside another dictionary. The globals() function just returns the global dictionary, anyway.

Joran Beasley · Accepted Answer · 2012-07-26 22:32:36Z

0

def foo(user,other_stuff):
     fname = "%s_hx"%user[key] #not sure where key is comming from... but would result in something like "bob_hx"
     with open(fname) as f:
          print f.read()

maybe?/

answered Jul 26, 2012 at 22:32

Joran Beasley

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Comments

Keith · Accepted Answer · 2012-07-27 00:31:48Z

0

Don't use the name as a variable. You can put your collection of dictionaries inside another, top-level, dictionary with those names as keys.

users = {
    "user1_hx": {"name": "User 1"},
    "user2_hx": {"name": "User 2"),
    }

etc.

Then access as:

realname = users["%s_hx" % name]["name"]

etc.

answered Jul 27, 2012 at 0:31

Keith

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