From b0ecd90dd89d254853bd02b4bfe7ca4e9e45860d Mon Sep 17 00:00:00 2001
From: "Mads M. Pedersen" <mmpe@dtu.dk>
Date: Tue, 11 Apr 2017 12:51:17 +0200
Subject: [PATCH] type in differentiation
---
wetb/signal/filters/_differentiation.py | 16 +++++++++++++---
wetb/signal/tests/test_differentiation.py | 2 ++
2 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/wetb/signal/filters/_differentiation.py b/wetb/signal/filters/_differentiation.py
index 16caa027..94406ca9 100644
--- a/wetb/signal/filters/_differentiation.py
+++ b/wetb/signal/filters/_differentiation.py
@@ -3,15 +3,19 @@ Created on 29. mar. 2017
@author: mmpe
'''
-from wetb.signal.filters.frq_filters import low_pass
+
import numpy as np
-def differentiation(x,sample_frq=None, cutoff_frq=None):
+def differentiation(x, type='center', sample_frq=None, cutoff_frq=None):
"""Differentiate the signal
Parameters
----------
x : array_like
The input signal
+ type : {'right','center','left'}
+ right: change from current to next observation\n
+ center: average change from previous to next observation\n
+ left: change from previous to current observation\n
sample_frq : int, float or None, optional
sample frequency of signal (only required if low pass filer is applied)
cutoff_frq : int, float or None, optional
@@ -30,8 +34,14 @@ def differentiation(x,sample_frq=None, cutoff_frq=None):
if cutoff_frq is not None:
assert sample_frq is not None, "Argument sample_frq must be set to apply low pass filter"
+ from wetb.signal.filters.frq_filters import low_pass
x = low_pass(x, sample_frq, cutoff_frq)
else:
x = np.array(x)
- dy = np.r_[x[1]-x[0], (x[2:]-x[:-2])/2, x[-1]-x[-2]]
+ if type=="left":
+ dy = np.r_[np.nan, x[1:]-x[:-1]]
+ if type=="center":
+ dy = np.r_[x[1]-x[0], (x[2:]-x[:-2])/2, x[-1]-x[-2]]
+ if type=="right":
+ dy = np.r_[x[1:]-x[:-1], np.nan]
return dy
\ No newline at end of file
diff --git a/wetb/signal/tests/test_differentiation.py b/wetb/signal/tests/test_differentiation.py
index 87538cdc..3abcdc0f 100644
--- a/wetb/signal/tests/test_differentiation.py
+++ b/wetb/signal/tests/test_differentiation.py
@@ -12,6 +12,8 @@ class Test(unittest.TestCase):
def testDifferentiation(self):
np.testing.assert_array_equal(differentiation([1,2,1,0,1,1]), [1,0,-1,0,.5,0])
+ np.testing.assert_array_equal(differentiation([1,2,1,0,1,1], 'left'), [np.nan, 1,-1,-1,1,0])
+ np.testing.assert_array_equal(differentiation([1,2,1,0,1,1], 'right'), [1,-1,-1,1,0, np.nan])
--
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