Another option might be numpy.asarray:
import numpy as np
a = ["1.1", "2.2", "3.2"]
b = np.asarray(a, dtype=np.float64, order='C')
For Python 2*:
print a, type(a), type(a[0])
print b, type(b), type(b[0])
resulting in:
['1.1', '2.2', '3.2'] <type 'list'> <type 'str'>
[1.1 2.2 3.2] <type 'numpy.ndarray'> <type 'numpy.float64'>