python - 从 pandas.Series 中选择局部最小值和最大值

Question

有一个scipy.signal.argrelextrema与 ndarray 一起使用的函数，但是当我尝试在 pandas.Series 上使用它时，它返回错误。将它与 pandas 一起使用的正确方法是什么？

import numpy as np
import pandas as pd
from scipy.signal import argrelextrema
s = pd.Series(randn(10), range(10))
s
argrelextrema(s, np.greater)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-13-f3812e58bbe4> in <module>()
      4 s = pd.Series(randn(10), range(10))
      5 s
----> 6 argrelextrema(s, np.greater)

/usr/lib/python2.7/dist-packages/scipy/signal/_peak_finding.pyc in argrelextrema(data, comparator, axis, order, mode)
    222     """
    223     results = _boolrelextrema(data, comparator,
--> 224                               axis, order, mode)
    225     return np.where(results)
    226 

/usr/lib/python2.7/dist-packages/scipy/signal/_peak_finding.pyc in _boolrelextrema(data, comparator, axis, order, mode)
     60 
     61     results = np.ones(data.shape, dtype=bool)
---> 62     main = data.take(locs, axis=axis, mode=mode)
     63     for shift in xrange(1, order + 1):
     64         plus = data.take(locs + shift, axis=axis, mode=mode)

TypeError: take() got an unexpected keyword argument 'mode'

Answer 1

你可能想像这样使用它，

argrelextrema(s.values, np.greater)

您目前正在使用完整的 pandas 系列，而 argrelextrema 需要一个 nd 数组。 s.values 为您提供 nd.array