Return array of indices to the minimum values along the given axis.
| Parameters : | axis : {None, integer} 
 fill_value : {var}, optional 
 out : {None, array}, optional 
  | 
|---|---|
| Returns : | {ndarray, scalar} : 
  | 
Examples
>>> x = np.ma.array(arange(4), mask=[1,1,0,0])
>>> x.shape = (2,2)
>>> print x
[[-- --]
 [2 3]]
>>> print x.argmin(axis=0, fill_value=-1)
[0 0]
>>> print x.argmin(axis=0, fill_value=9)
[1 1]