HyperSpy API has changed in version 2.0, see the release notes!

Speeding up operations#

Reusing a Signal for output#

Many signal methods create and return a new signal. For fast operations, the new signal creation time is non-negligible. Also, when the operation is repeated many times, for example in a loop, the cumulative creation time can become significant. Therefore, many operations on BaseSignal accept an optional argument out. If an existing signal is passed to out, the function output will be placed into that signal, instead of being returned in a new signal. The following example shows how to use this feature to slice a BaseSignal. It is important to know that the BaseSignal instance passed in the out argument must be well-suited for the purpose. Often this means that it must have the same axes and data shape as the BaseSignal that would normally be returned by the operation.

>>> s = hs.signals.Signal1D(np.arange(10))
>>> s_sum = s.sum(0)
>>> s_sum.data
>>> s.isig[:5].sum(0, out=s_sum)
>>> s_sum.data
>>> s_roi = s.isig[:3]
>>> s_roi
<Signal1D, title: , dimensions: (|3)>
>>> s.isig.__getitem__(slice(None, 5), out=s_roi)
>>> s_roi
<Signal1D, title: , dimensions: (|5)>