eric.le.bi...@spectro.jussieu.fr wrote:
Hello,
Is there a way to easily build an object that behaves exactly like a
float, but whose value can be changed? The goal is to maintain a list
[x, y,…] of these float-like objects, and to modify their value on the
fly (with something like x.value = 3.14) so that any expression like "x
+y" uses the new value.
Hi Eric,
Numpy's array object can do something like what you want:
In [27]: x=array(0.0)
In [28]: print x, sin(x)
0.0 0.0
In [29]: x.itemset(pi/2)
In [30]: print x, sin(x)
1.57079632679 1.0
Not sure if this a recommended way of using array or not, but it seems
to work. The problem is that any calculation you do with such an object
will result in a float, and not another numpy array (although inplace
operations work):
In [40]: print (x*2).__class__
<type 'numpy.float64'>
In [41]: x *= 2
In [42]: print x.__class__
<type 'numpy.ndarray'>
So it's not a perfect solution, but it might be OK for what you need.
Dan
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