在具有4GB内存的计算机上,这种简单的插值会导致内存错误:
(基于: http://docs.scipy.org/doc/scipy/reference/tutorial/interpolate.html)
import numpy as np
from scipy.interpolate import interp1d
x = np.linspace(0, 10, 80000)
y = np.cos(-x**2/8.0)
f2 = interp1d(x, y, kind='cubic')
我想过将数据切割成块,但有没有办法可以执行这种三次样条插值而不需要太多内存?
为什么它甚至遇到麻烦?
如果您在发生错误时查看回溯,您会看到如下内容:
---------------------------------------------------------------------------
MemoryError Traceback (most recent call last)
<ipython-input-4-1e538e8d766e> in <module>()
----> 1 f2 = interp1d(x, y, kind='cubic')
/home/warren/local_scipy/lib/python2.7/site-packages/scipy/interpolate/interpolate.py in __init__(self, x, y, kind, axis, copy, bounds_error, fill_value)
390 else:
391 minval = order + 1
--> 392 self._spline = splmake(x, y, order=order)
393 self._call = self.__class__._call_spline
394
/home/warren/local_scipy/lib/python2.7/site-packages/scipy/interpolate/interpolate.py in splmake(xk, yk, order, kind, conds)
1754
1755 # the constraint matrix
-> 1756 B = _fitpack._bsplmat(order, xk)
1757 coefs = func(xk, yk, order, conds, B)
1758 return xk, coefs, order
MemoryError:
失败的功能是 scipy.interpolate._fitpack._bsplmat(order, xk)
。此函数创建一个具有形状的64位浮点数的二维数组 (len(xk), len(xk) + order - 1)
。在你的情况下,这超过51GB。
代替 interp1d
, 看看 InterpolatedUnivariateSpline
适合你。例如,
import numpy as np
from scipy.interpolate import InterpolatedUnivariateSpline
x = np.linspace(0, 10, 80000)
y = np.cos(-x**2/8.0)
f2 = InterpolatedUnivariateSpline(x, y, k=3)
我没有得到内存错误。