Using numpy to select the data
# selected with one condition
data_selected = data[data[:, 0]<2]
# more than one condition
data_selected = data[np.where((x1 <= data[:, 0]) & (data[:, 0] <x2))]
# or
data_selected = data[np.where((x1 <= data[:, 0]) | (data[:, 0] <x2))]
