Suppose I have a list X = [a, b, c] where a, b, c are instances of the same class C. Now, all these instances a,b,c, have a variable called v, a.v, b.v, c.v ... I simply want a list Y = [a.v, b.v, c.v]
Is there a nice command to do this? The best way I can think of is:
Y = []
for i in X
Y.append(i.v)
But it doesn't seem very elegant ~ since this needs to be repeated for any given "v" Any suggestions? I couldn't figure out a way to use "map" to do this.
That should work:
Y = [x.v for x in X]
The list comprehension is the way to go.
But you also said you don't know how to use map to do it. Now, I would not recommend to use map for this at all, but it can be done:
map( lambda x: x.v, X)
that is, you create an anonymous function (a lambda) to return that attribute.
If you prefer to use the python library methods (know thy tools...) then something like:
map(operator.attrgetter("v"),X)
should also work.
map .. ah wait how about itemgetter. +1 for you.I would do a list comprehension:
Y = [ i.v for i in X ]
It is shorter and more conveniant.
