Python中是否有SciPy函数或NumPy函数或模块来计算给定特定窗口的1D数组的运行平均值?
当前回答
有点晚了,但我已经做了我自己的小函数,它不环绕端点或垫与零,然后用于查找平均值。进一步的处理是,它还在线性间隔点上对信号进行重新采样。随意定制代码以获得其他特性。
该方法是一个简单的矩阵乘法与规范化高斯核。
def running_mean(y_in, x_in, N_out=101, sigma=1):
'''
Returns running mean as a Bell-curve weighted average at evenly spaced
points. Does NOT wrap signal around, or pad with zeros.
Arguments:
y_in -- y values, the values to be smoothed and re-sampled
x_in -- x values for array
Keyword arguments:
N_out -- NoOf elements in resampled array.
sigma -- 'Width' of Bell-curve in units of param x .
'''
import numpy as np
N_in = len(y_in)
# Gaussian kernel
x_out = np.linspace(np.min(x_in), np.max(x_in), N_out)
x_in_mesh, x_out_mesh = np.meshgrid(x_in, x_out)
gauss_kernel = np.exp(-np.square(x_in_mesh - x_out_mesh) / (2 * sigma**2))
# Normalize kernel, such that the sum is one along axis 1
normalization = np.tile(np.reshape(np.sum(gauss_kernel, axis=1), (N_out, 1)), (1, N_in))
gauss_kernel_normalized = gauss_kernel / normalization
# Perform running average as a linear operation
y_out = gauss_kernel_normalized @ y_in
return y_out, x_out
正弦信号加正态分布噪声的一个简单用法:
其他回答
或用于python计算的模块
在我在Tradewave.net的测试中,TA-lib总是赢:
import talib as ta
import numpy as np
import pandas as pd
import scipy
from scipy import signal
import time as t
PAIR = info.primary_pair
PERIOD = 30
def initialize():
storage.reset()
storage.elapsed = storage.get('elapsed', [0,0,0,0,0,0])
def cumsum_sma(array, period):
ret = np.cumsum(array, dtype=float)
ret[period:] = ret[period:] - ret[:-period]
return ret[period - 1:] / period
def pandas_sma(array, period):
return pd.rolling_mean(array, period)
def api_sma(array, period):
# this method is native to Tradewave and does NOT return an array
return (data[PAIR].ma(PERIOD))
def talib_sma(array, period):
return ta.MA(array, period)
def convolve_sma(array, period):
return np.convolve(array, np.ones((period,))/period, mode='valid')
def fftconvolve_sma(array, period):
return scipy.signal.fftconvolve(
array, np.ones((period,))/period, mode='valid')
def tick():
close = data[PAIR].warmup_period('close')
t1 = t.time()
sma_api = api_sma(close, PERIOD)
t2 = t.time()
sma_cumsum = cumsum_sma(close, PERIOD)
t3 = t.time()
sma_pandas = pandas_sma(close, PERIOD)
t4 = t.time()
sma_talib = talib_sma(close, PERIOD)
t5 = t.time()
sma_convolve = convolve_sma(close, PERIOD)
t6 = t.time()
sma_fftconvolve = fftconvolve_sma(close, PERIOD)
t7 = t.time()
storage.elapsed[-1] = storage.elapsed[-1] + t2-t1
storage.elapsed[-2] = storage.elapsed[-2] + t3-t2
storage.elapsed[-3] = storage.elapsed[-3] + t4-t3
storage.elapsed[-4] = storage.elapsed[-4] + t5-t4
storage.elapsed[-5] = storage.elapsed[-5] + t6-t5
storage.elapsed[-6] = storage.elapsed[-6] + t7-t6
plot('sma_api', sma_api)
plot('sma_cumsum', sma_cumsum[-5])
plot('sma_pandas', sma_pandas[-10])
plot('sma_talib', sma_talib[-15])
plot('sma_convolve', sma_convolve[-20])
plot('sma_fftconvolve', sma_fftconvolve[-25])
def stop():
log('ticks....: %s' % info.max_ticks)
log('api......: %.5f' % storage.elapsed[-1])
log('cumsum...: %.5f' % storage.elapsed[-2])
log('pandas...: %.5f' % storage.elapsed[-3])
log('talib....: %.5f' % storage.elapsed[-4])
log('convolve.: %.5f' % storage.elapsed[-5])
log('fft......: %.5f' % storage.elapsed[-6])
结果:
[2015-01-31 23:00:00] ticks....: 744
[2015-01-31 23:00:00] api......: 0.16445
[2015-01-31 23:00:00] cumsum...: 0.03189
[2015-01-31 23:00:00] pandas...: 0.03677
[2015-01-31 23:00:00] talib....: 0.00700 # <<< Winner!
[2015-01-31 23:00:00] convolve.: 0.04871
[2015-01-31 23:00:00] fft......: 0.22306
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)
另一种不使用numpy或pandas找到移动平均线的方法
import itertools
sample = [2, 6, 10, 8, 11, 10]
list(itertools.starmap(
lambda a,b: b/a,
enumerate(itertools.accumulate(sample), 1))
)
将打印[2.0,4.0,6.0,6.5,7.4,7.83333333333333333]
2.0 = (2)/1 4.0 is (2 + 6) / 2 6.0 = (2 + 6 + 10) / 3 .
有关现成的解决方案,请参见https://scipy-cookbook.readthedocs.io/items/SignalSmooth.html。 它提供了平窗类型的运行平均值。请注意,这比简单的do-it-yourself卷积方法要复杂一些,因为它试图通过反射数据来处理数据开头和结尾的问题(在您的情况下可能有效,也可能无效……)。
首先,你可以试着:
a = np.random.random(100)
plt.plot(a)
b = smooth(a, window='flat')
plt.plot(b)
有点晚了,但我已经做了我自己的小函数,它不环绕端点或垫与零,然后用于查找平均值。进一步的处理是,它还在线性间隔点上对信号进行重新采样。随意定制代码以获得其他特性。
该方法是一个简单的矩阵乘法与规范化高斯核。
def running_mean(y_in, x_in, N_out=101, sigma=1):
'''
Returns running mean as a Bell-curve weighted average at evenly spaced
points. Does NOT wrap signal around, or pad with zeros.
Arguments:
y_in -- y values, the values to be smoothed and re-sampled
x_in -- x values for array
Keyword arguments:
N_out -- NoOf elements in resampled array.
sigma -- 'Width' of Bell-curve in units of param x .
'''
import numpy as np
N_in = len(y_in)
# Gaussian kernel
x_out = np.linspace(np.min(x_in), np.max(x_in), N_out)
x_in_mesh, x_out_mesh = np.meshgrid(x_in, x_out)
gauss_kernel = np.exp(-np.square(x_in_mesh - x_out_mesh) / (2 * sigma**2))
# Normalize kernel, such that the sum is one along axis 1
normalization = np.tile(np.reshape(np.sum(gauss_kernel, axis=1), (N_out, 1)), (1, N_in))
gauss_kernel_normalized = gauss_kernel / normalization
# Perform running average as a linear operation
y_out = gauss_kernel_normalized @ y_in
return y_out, x_out
正弦信号加正态分布噪声的一个简单用法:
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