我有以下范围的numpy数据（usec时间戳的增量）：

array([ 4.312,  4.317,  4.316,  4.32 ,  4.316,  4.316,  4.319,  4.317,
    4.317,  4.316,  4.318,  4.316,  4.318,  4.316,  4.318,  4.317,
    4.317,  4.317,  4.316,  4.317,  4.318,  4.316,  4.318,  4.316,
    4.318,  4.316,  4.317,  4.317,  4.318,  4.316,  4.317,  4.317,
    4.317,  4.317,  4.317,  4.316,  4.319,  4.315,  4.319,  4.315,
    4.319,  4.315,  4.316,  4.319,  4.317,  4.317,  4.317,  4.318,
    4.315,  4.317,  4.317,  4.317,  4.319,  4.314,  4.32 ,  4.315,
    4.317,  4.318,  4.315,  4.318,  4.317,  4.317,  4.317,  4.316,
    4.317,  4.318,  4.317,  4.317,  4.317,  4.315,  4.319,  4.317,
    4.315,  4.319,  4.316,  4.318,  4.318,  4.315,  4.318,  4.317,
    4.317,  4.321])

当我使用matplotlib.pyplot绘图时：

import matplotlib.pyplot as plt
 plt.plot( deltas ) 
 plt.show()

我得到了下面的情节。为什么Y轴以这种方式缩放？如何将Y轴标记为数据，而不是数据的偏移？有时图是“+4.nnn”，有时不是（取决于数据范围？）.
“奇怪地”策划：

“正确”绘制：