Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #17480

Re: Newbie Question: Obtain element from list of tuples

Show all headers | View raw

On Mon, Dec 19, 2011 at 6:41 AM, HoneyMonster <someone@someplace.invalid> wrote:
> My question is doubtless a very easy one to answer: Say I want the ninth
> element in the twentieth tuple put into variable PID, I can do this,
> bearing in mind that numbering starts at zero:
>
> tup = recs[19]
> PID = tup[8]
>
> But there must be an easier way; i.e. to do it in one go without the
> extra variable. How do I achieve that please?

The specific answer has already been given, but I'd like to fill in
the generality. In Python, everything's an object; if you can do
something with a variable, you can do it with an expression too. I
don't know what your function call is to obtain your record list, but
imagine it's:

recs = conn.query("SELECT * FROM some_table")

Then you can actually do all of this in a single statement. It's not
usually what you'll want to do, but this is legal:

pid = conn.query("SELECT * FROM some_table")[19][8]

If you're absolutely certain that you'll always get precisely one
value from a query, this becomes rather more useful:

mode = conn.query("SELECT mode FROM config WHERE id=5")[0][0]

In any case: You can work with a function's return value directly,
without first storing it in a temporary variable.

Hope that helps!

Chris Angelico

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Newbie Question: Obtain element from list of tuples HoneyMonster <someone@someplace.invalid> - 2011-12-18 19:41 +0000
  Re: Newbie Question: Obtain element from list of tuples Arnaud Delobelle <arnodel@gmail.com> - 2011-12-18 19:49 +0000
  Re: Newbie Question: Obtain element from list of tuples Roy Smith <roy@panix.com> - 2011-12-18 15:04 -0500
    Re: Newbie Question: Obtain element from list of tuples HoneyMonster <someone@someplace.invalid> - 2011-12-18 20:22 +0000
      Re: Newbie Question: Obtain element from list of tuples Roy Smith <roy@panix.com> - 2011-12-18 15:25 -0500
    Re: Newbie Question: Obtain element from list of tuples alex23 <wuwei23@gmail.com> - 2011-12-18 18:35 -0800
      Re: Newbie Question: Obtain element from list of tuples Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-19 03:00 +0000
        Re: Newbie Question: Obtain element from list of tuples "Frank Millman" <frank@chagford.com> - 2011-12-19 08:46 +0200
          Re: Newbie Question: Obtain element from list of tuples DevPlayer <devplayer@gmail.com> - 2011-12-19 07:37 -0800
          Re: Newbie Question: Obtain element from list of tuples alex23 <wuwei23@gmail.com> - 2011-12-19 19:53 -0800
  Re: Newbie Question: Obtain element from list of tuples Chris Angelico <rosuav@gmail.com> - 2011-12-19 07:51 +1100
    Re: Newbie Question: Obtain element from list of tuples Roy Smith <roy@panix.com> - 2011-12-18 16:10 -0500
    Re: Newbie Question: Obtain element from list of tuples HoneyMonster <someone@someplace.invalid> - 2011-12-18 22:55 +0000
      Re: Newbie Question: Obtain element from list of tuples Chris Angelico <rosuav@gmail.com> - 2011-12-19 10:40 +1100
        Re: Newbie Question: Obtain element from list of tuples HoneyMonster <someone@someplace.invalid> - 2011-12-20 00:59 +0000

csiph-web