另一个解决方案是使用标准库和deque:

from collections import deque
import itertools

def moving_average(iterable, n=3):
    # http://en.wikipedia.org/wiki/Moving_average
    it = iter(iterable) 
    # create an iterable object from input argument
    d = deque(itertools.islice(it, n-1))  
    # create deque object by slicing iterable
    d.appendleft(0)
    s = sum(d)
    for elem in it:
        s += elem - d.popleft()
        d.append(elem)
        yield s / n

# example on how to use it
for i in  moving_average([40, 30, 50, 46, 39, 44]):
    print(i)

# 40.0
# 42.0
# 45.0
# 43.0

如果你必须为非常小的数组(少于200个元素)重复这样做，我发现只用线性代数就能得到最快的结果。 最慢的部分是建立你的乘法矩阵y，你只需要做一次，但之后可能会更快。

import numpy as np
import random 

N = 100      # window size
size =200     # array length

x = np.random.random(size)
y = np.eye(size, dtype=float)

# prepare matrix
for i in range(size):
  y[i,i:i+N] = 1./N
  
# calculate running mean
z = np.inner(x,y.T)[N-1:]

更新:已经提出了更有效的解决方案，scipy的uniform_filter1d可能是“标准”第三方库中最好的，还有一些更新的或专门的库可用。

你可以用np。卷积得到:

np.convolve(x, np.ones(N)/N, mode='valid')

解释

The running mean is a case of the mathematical operation of convolution. For the running mean, you slide a window along the input and compute the mean of the window's contents. For discrete 1D signals, convolution is the same thing, except instead of the mean you compute an arbitrary linear combination, i.e., multiply each element by a corresponding coefficient and add up the results. Those coefficients, one for each position in the window, are sometimes called the convolution kernel. The arithmetic mean of N values is (x_1 + x_2 + ... + x_N) / N, so the corresponding kernel is (1/N, 1/N, ..., 1/N), and that's exactly what we get by using np.ones(N)/N.

边缘

np的模态参数。Convolve指定如何处理边缘。我在这里选择有效模式，因为我认为这是大多数人期望的运行方式，但您可能有其他优先级。下面是一个图表，说明了模式之间的差异:

import numpy as np
import matplotlib.pyplot as plt
modes = ['full', 'same', 'valid']
for m in modes:
    plt.plot(np.convolve(np.ones(200), np.ones(50)/50, mode=m));
plt.axis([-10, 251, -.1, 1.1]);
plt.legend(modes, loc='lower center');
plt.show()

对于一个简短、快速的解决方案，在一个循环中完成所有事情，没有依赖关系，下面的代码工作得很好。

mylist = [1, 2, 3, 4, 5, 6, 7]
N = 3
cumsum, moving_aves = [0], []

for i, x in enumerate(mylist, 1):
    cumsum.append(cumsum[i-1] + x)
    if i>=N:
        moving_ave = (cumsum[i] - cumsum[i-N])/N
        #can do stuff with moving_ave here
        moving_aves.append(moving_ave)

出于教学目的，让我再添加两个Numpy解决方案(比cumsum解决方案慢):

import numpy as np
from numpy.lib.stride_tricks import as_strided

def ra_strides(arr, window):
    ''' Running average using as_strided'''
    n = arr.shape[0] - window + 1
    arr_strided = as_strided(arr, shape=[n, window], strides=2*arr.strides)
    return arr_strided.mean(axis=1)

def ra_add(arr, window):
    ''' Running average using add.reduceat'''
    n = arr.shape[0] - window + 1
    indices = np.array([0, window]*n) + np.repeat(np.arange(n), 2)
    arr = np.append(arr, 0)
    return np.add.reduceat(arr, indices )[::2]/window

使用的函数:as_strided, add.reduceat

从其他答案来看，我不认为这是问题所要求的，但我需要保持一个不断增长的值列表的运行平均值。

因此，如果你想保持从某个地方(站点，测量设备等)获取的值的列表和最近n个值更新的平均值，你可以使用下面的代码，这将最大限度地减少添加新元素的工作:

class Running_Average(object):
    def __init__(self, buffer_size=10):
        """
        Create a new Running_Average object.

        This object allows the efficient calculation of the average of the last
        `buffer_size` numbers added to it.

        Examples
        --------
        >>> a = Running_Average(2)
        >>> a.add(1)
        >>> a.get()
        1.0
        >>> a.add(1)  # there are two 1 in buffer
        >>> a.get()
        1.0
        >>> a.add(2)  # there's a 1 and a 2 in the buffer
        >>> a.get()
        1.5
        >>> a.add(2)
        >>> a.get()  # now there's only two 2 in the buffer
        2.0
        """
        self._buffer_size = int(buffer_size)  # make sure it's an int
        self.reset()

    def add(self, new):
        """
        Add a new number to the buffer, or replaces the oldest one there.
        """
        new = float(new)  # make sure it's a float
        n = len(self._buffer)
        if n < self.buffer_size:  # still have to had numbers to the buffer.
            self._buffer.append(new)
            if self._average != self._average:  # ~ if isNaN().
                self._average = new  # no previous numbers, so it's new.
            else:
                self._average *= n  # so it's only the sum of numbers.
                self._average += new  # add new number.
                self._average /= (n+1)  # divide by new number of numbers.
        else:  # buffer full, replace oldest value.
            old = self._buffer[self._index]  # the previous oldest number.
            self._buffer[self._index] = new  # replace with new one.
            self._index += 1  # update the index and make sure it's...
            self._index %= self.buffer_size  # ... smaller than buffer_size.
            self._average -= old/self.buffer_size  # remove old one...
            self._average += new/self.buffer_size  # ...and add new one...
            # ... weighted by the number of elements.

    def __call__(self):
        """
        Return the moving average value, for the lazy ones who don't want
        to write .get .
        """
        return self._average

    def get(self):
        """
        Return the moving average value.
        """
        return self()

    def reset(self):
        """
        Reset the moving average.

        If for some reason you don't want to just create a new one.
        """
        self._buffer = []  # could use np.empty(self.buffer_size)...
        self._index = 0  # and use this to keep track of how many numbers.
        self._average = float('nan')  # could use np.NaN .

    def get_buffer_size(self):
        """
        Return current buffer_size.
        """
        return self._buffer_size

    def set_buffer_size(self, buffer_size):
        """
        >>> a = Running_Average(10)
        >>> for i in range(15):
        ...     a.add(i)
        ...
        >>> a()
        9.5
        >>> a._buffer  # should not access this!!
        [10.0, 11.0, 12.0, 13.0, 14.0, 5.0, 6.0, 7.0, 8.0, 9.0]

        Decreasing buffer size:
        >>> a.buffer_size = 6
        >>> a._buffer  # should not access this!!
        [9.0, 10.0, 11.0, 12.0, 13.0, 14.0]
        >>> a.buffer_size = 2
        >>> a._buffer
        [13.0, 14.0]

        Increasing buffer size:
        >>> a.buffer_size = 5
        Warning: no older data available!
        >>> a._buffer
        [13.0, 14.0]

        Keeping buffer size:
        >>> a = Running_Average(10)
        >>> for i in range(15):
        ...     a.add(i)
        ...
        >>> a()
        9.5
        >>> a._buffer  # should not access this!!
        [10.0, 11.0, 12.0, 13.0, 14.0, 5.0, 6.0, 7.0, 8.0, 9.0]
        >>> a.buffer_size = 10  # reorders buffer!
        >>> a._buffer
        [5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0]
        """
        buffer_size = int(buffer_size)
        # order the buffer so index is zero again:
        new_buffer = self._buffer[self._index:]
        new_buffer.extend(self._buffer[:self._index])
        self._index = 0
        if self._buffer_size < buffer_size:
            print('Warning: no older data available!')  # should use Warnings!
        else:
            diff = self._buffer_size - buffer_size
            print(diff)
            new_buffer = new_buffer[diff:]
        self._buffer_size = buffer_size
        self._buffer = new_buffer

    buffer_size = property(get_buffer_size, set_buffer_size)

你可以测试它，例如:

def graph_test(N=200):
    import matplotlib.pyplot as plt
    values = list(range(N))
    values_average_calculator = Running_Average(N/2)
    values_averages = []
    for value in values:
        values_average_calculator.add(value)
        values_averages.append(values_average_calculator())
    fig, ax = plt.subplots(1, 1)
    ax.plot(values, label='values')
    ax.plot(values_averages, label='averages')
    ax.grid()
    ax.set_xlim(0, N)
    ax.set_ylim(0, N)
    fig.show()

这使: