I was thinking about something like the following; a=[ t**n for n in range(4) ]
Traceback (most recent call last):
File "<stdin>", line 1, in ?
NameError: name 't' is not defined
or
a=[ lambda t: t**n for n in range(4) ]
t=2
a
[<function <lambda> at 0x403dcc6c>, <function <lambda> at 0x403dcca4>,
<function <lambda> at 0x403dccdc>, <function <lambda> at 0x403dcd14>] t=3
a
[<function <lambda> at 0x403dcc6c>, <function <lambda> at 0x403dcca4>,
<function <lambda> at 0x403dccdc>, <function <lambda> at 0x403dcd14>]
is something like that possible? Will you give me advice about that? 17  2005  me************* @gmail.com wrote: I was thinking about something like the following;
a=[ t**n for n in range(4) ]
Traceback (most recent call last):
File "<stdin>", line 1, in ?
NameError: name 't' is not defined
or
a=[ lambda t: t**n for n in range(4) ]
t=2
a
Perhaps you mean: a = lambda t: [t**n for n in range(4)]
a(2)
[1, 2, 4, 8]
but that is better written as: def a(t):
... return [t**n for n in range(4)]
...
a(2)
[1, 2, 4, 8]
Michael
Please post a description of what you are trying to
accomplish instead of asking us to take your possible
solution and try to figure out what the problem was.
You can do:
def foo(t, r):
return [t**n for n in range(r)]
a=foo(2, 4)
a
[1, 2, 4, 8]
a=foo(3,6)
a
[1, 3, 9, 27, 81, 243]
but I don't really know what you want.
Larry me************* @gmail.com wrote: I was thinking about something like the following;
a=[ t**n for n in range(4) ]
Traceback (most recent call last):
File "<stdin>", line 1, in ?
NameError: name 't' is not defined
or
a=[ lambda t: t**n for n in range(4) ]
t=2
a
[<function <lambda> at 0x403dcc6c>, <function <lambda> at 0x403dcca4>,
<function <lambda> at 0x403dccdc>, <function <lambda> at 0x403dcd14>]
t=3
a
[<function <lambda> at 0x403dcc6c>, <function <lambda> at 0x403dcca4>,
<function <lambda> at 0x403dccdc>, <function <lambda> at 0x403dcd14>]
is something like that possible? Will you give me advice about that?
Thanx for your replies.
I'm looking for array of functions.
Something like a=[ sin(x) , cos(x) ] x=0.0
a
[0, 1] x=1.0
a
....
of course it can be made by def cratearray(x):
.... ~~~~
.... return a
a=createarray(1 .0)
but this isn't what i am asking for. something automized. me************* @gmail.com wrote: Thanx for your replies.
I'm looking for array of functions.
Something like a=[ sin(x) , cos(x) ]
x=0.0
a
[0, 1]
x=1.0
a
...
of course it can be made by
def cratearray(x):
... ~~~~
... return a
a=createarray(1 .0)
but this isn't what i am asking for. something automized.
Still, guessing, but perhaps this:
def make_func_map(* funcs):
... def f(x):
... return [func(x) for func in funcs]
... return f
... from math import sin, cos, pi
a = make_func_map(s in, cos)
a(0)
[0.0, 1.0] a(pi)
[1.2246063538223 773e-016, -1.0]
Michael
On Friday 22 April 2005 05:18 pm, me************* @gmail.com wrote: Thanx for your replies.
I'm looking for array of functions.
Something like a=[ sin(x) , cos(x) ]
You had a list of lambda functions in your first post and in the
subject line still. How is that not what you wanted?
If you want an *answer*, you need to ask a *question*.
Perhaps you don't know how to call such functions? E.g.:
a=[ lambda t: t**n for n in range(4) ] a[2](3)
27
If you want to see *names* for the functions, you have two
choices: either used named functions,
def unity(t): return 1
def identity(t): return t
def square(t): return t**2
def cube(t): return t**3
a = [unity, identity, square, cube]
a
[<function unity at 0x401e609c>, <function identity at 0x401e6b54>,
<function square at 0x401e6b8c>, <function cube at 0x401e6ca4>]
or replace the list with a dictionary, e.g.:
a = dict([('t**%d' % n, lambda t: t**n) for n in range(4)])
a
{'t**0': <function <lambda> at 0x401e6bc4>, 't**1': <function <lambda> at 0x401e6bfc>,
't**2': <function <lambda> at 0x401e6c34>, 't**3': <function <lambda> at 0x401e6c6c>} a.keys()
['t**0', 't**1', 't**2', 't**3'] a['t**3'](4)
64
--
Terry Hancock ( hancock at anansispacework s.com )
Anansi Spaceworks http://www.anansispaceworks.com
Terry Hancock wrote: On Friday 22 April 2005 05:18 pm, me************* @gmail.com wrote:
Perhaps you don't know how to call such functions? E.g.:
a=[ lambda t: t**n for n in range(4) ]
a[2](3)
27
Didn't you notice this was a funny value?
Maybe this example will show you what is going wrong:
a[0](3)
27 n = 10
a[3](2)
1024
See, the body of your anonymous function just looks for "the current
value of n" when it is _invoked_, not when it is _defined_.
Perhaps you mean:
a = [lambda t, n=n: t**n for n in range(4)]
which captures the value of n as a default parameter at definition time.
In that case you get:
a = [lambda t, n=n: t**n for n in range(4)]
a[0](1024)
1 a[1](512)
512 a[2](16)
256 a[3](4)
64
--Scott David Daniels Sc***********@A cm.Org
Thanx.
It just popped in my mind.
in 3d programming there are transformation matrices like
a=[[cos(x),sin(x),0],[-sin(x),cos(x),0],[0,0,1]]
it is a 3x3 matrix. never changes during program.
it can be defined like def transmat(x):
.... dummy=[[0,0,0],[0,0,0],[0,0,0]]
.... dummy[0][0]=cos(x)
.... ~~~~~~
.... return dummy
a=transmat(1.0)
it is usual way for this.
i wonder if there is an automatic way to make that without calling a
function.
an automatic way that depends on changing the value of x. as each time
x=something used the whole matrix changes automaticly.
or maybe i am just dreaming. :)
On 22 Apr 2005 14:41:45 -0700, me************* @gmail.com
<me************ *@gmail.com> wrote: I was thinking about something like the following;
a=[ t**n for n in range(4) ] Traceback (most recent call last):
File "<stdin>", line 1, in ?
NameError: name 't' is not defined
or
a=[ lambda t: t**n for n in range(4) ]
t=2
a [<function <lambda> at 0x403dcc6c>, <function <lambda> at 0x403dcca4>,
<function <lambda> at 0x403dccdc>, <function <lambda> at 0x403dcd14>] t=3
a [<function <lambda> at 0x403dcc6c>, <function <lambda> at 0x403dcca4>,
<function <lambda> at 0x403dccdc>, <function <lambda> at 0x403dcd14>]
Well, everybody else took away your lambda (greedy people!) but I'm
here to say that it doesn't *have* to go away. I didn't think this
would be possible, but it is:
t = 2
[(lambda n: t**n)(n) for n in range(4)]
[1, 2, 4, 8] t = 3
[(lambda n: t**n)(n) for n in range(4)]
[1, 3, 9, 27]
I just thought that was kinda neat. If you wanted to obfuscate some
python, this would be an awesome trick - hide the value of t somewhere
early in the function then pull a variation of this out later.
Peace
Bill Mill
bill.mill at gmail.com
On 22 Apr 2005 15:18:53 -0700, me************* @gmail.com wrote: Thanx for your replies.
I'm looking for array of functions.
Something like a=[ sin(x) , cos(x) ]
x=0.0
a[0, 1] x=1.0
a...
of course it can be made by def cratearray(x):... ~~~~
... return a
a=createarray( 1.0)
but this isn't what i am asking for. something automized.
I still don't know what you are asking for, but here is a toy,
whose code you will be able to improve on later, but at least
provides concrete behavior that you can comment on, and maybe
explain what you are really asking for.
class FunArray(object ):
... def __init__(self, *funs):
... self.__dict__['_funs'] = funs
... self.__dict__['_names'] = []
... vars
... def __getattribute_ _(self, attr):
... if attr.startswith ('_') or hasattr(type(se lf), attr):
... return object.__getatt ribute__(self, attr)
... v = vars(self).get( attr)
... if v is None: return ['%r is not set'%attr]
... return [f(v) for f in self._funs]
... def __setattr__(sel f, attr, v):
... if attr.startswith ('_'): raise AttributeError, attr
... else:
... if attr in self._names: self._names.rem ove(attr)
... self._names.app end(attr)
... self.__dict__[attr] = v
... def __repr__(self):
... last = self._names and self._names[-1] or '??'
... d= vars(self)
... return '<FunArray names: %s\n %r => %s>'% (
... ', '.join(['%s=%r'%(k, d[k]) for k in self._names]),
... last, repr(getattr(se lf, last)))
... from math import sin, cos, pi
a = FunArray(sin, cos)
a.x = 0.0
a
<FunArray names: x=0.0
'x' => [0.0, 1.0]> a.x
[0.0, 1.0] a.y = 1.0
a.y
[0.8414709848078 965, 0.5403023058681 3977] a
<FunArray names: x=0.0, y=1.0
'y' => [0.8414709848078 965, 0.5403023058681 3977]> a.z = pi/3
a
<FunArray names: x=0.0, y=1.0, z=1.04719755119 65976
'z' => [0.8660254037844 386, 0.5000000000000 0011]> a.x = pi/6
a
<FunArray names: y=1.0, z=1.04719755119 65976, x=0.52359877559 829882
'x' => [0.4999999999999 9994, 0.8660254037844 3871]
If you just want an interactive calculator that acts according to your taste,
you can program one to prompt and read (use raw_input, not input BTW) what you
type in and calculate and print whatever form of result you'd like. See the cmd
module for one way not to reinvent some wheels.
But why not spend some time with the tutorials, so have a few more cards in your deck
before you try to play for real? ;-)
Regards,
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