Rename signal -> signals

signals/__init__.py

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+# __init__.py
+# Eryn Wells <eryn@erynwells.me>
+
+from . import waves
+from . import domain
+
+__all__ = ['domain', 'waves']

signals/domain.py

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+# domain.py
+# Eryn Wells <eryn@erynwells.me>
+'''
+Some utilities for dealing with signal domains: time, frequency, etc.
+'''
+
+import numpy as np
+
+__default_time = 2.0
+__default_steps = 200
+
+class Time:
+    __DefaultTime = 2.0
+    __DefaultSteps = 200
+
+    def __init__(self, sec=__DefaultTime, samples=__DefaultSteps):
+        self.sec = sec
+        self.samples = samples
+        self._domain = None
+
+    @property
+    def domain(self):
+        if self._domain == None:
+            self._domain = np.linspace(0, self.sec, num=self.samples + 1)
+        return self._domain
+
+    @property
+    def rate(self):
+        '''Number of samples per second.'''
+        return self.samples / self.sec
+
+    @property
+    def interval(self):
+        '''Amount of time between samples, in seconds.'''
+        return self.sec / self.samples
+
+    def __str__(self):
+        return repr(self)
+
+    def __repr__(self):
+        return '{}(sec={}, samples={})'.format(self.__class__.__name__, self.sec, self.samples)

signals/waves.py

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+# waves.py
+# Eryn Wells <eryn@erynwells.me>
+'''
+Several functions for creating audio waves.
+'''
+
+import numpy as np
+
+__default_num_harmonics = 10
+
+def sine(domain, freq=1.0):
+    '''Render a sine wave in the given domain with the specified frequency.'''
+    return np.sin(2.0 * np.pi * freq * domain)
+
+def saw(domain, freq=1.0, num_harmonics=__default_num_harmonics):
+    '''
+    Render a saw wave in the given domain at the specified frequency.
+
+    This function produces a saw wave by computing the first `harmonics` terms of the
+    infinite series defining its shape.
+    '''
+    harmonics = np.asarray([1.0 / h * sine(domain, freq=freq * h) for h in range(1, num_harmonics)])
+    wave = np.sum(harmonics, axis=0)
+    return wave
+
+def square(domain, freq=1, num_harmonics=__default_num_harmonics):
+    '''
+    Render a square wave in the given domain at the specified frequency.
+
+    This function produces a saw wave by computing the first `harmonics` terms of the
+    infinite series defining its shape.
+    '''
+    harmonics = np.asarray([1.0 / h * sine(domain, freq=freq * h) for h in range(1, num_harmonics, 2)])
+    wave = np.sum(harmonics, axis=0)
+    return wave
+
+def triangle(domain, freq=1, num_harmonics=__default_num_harmonics):
+    '''
+    Render a triangle wave in the given domain at the specified frequency.
+
+    This function produces a saw wave by computing the first `num_harmonics` terms of the
+    infinite series defining its shape.
+    '''
+    def label(i):
+        return 2.0 * i + 1.0
+    harmonics = np.asarray([((-1) ** h) * (label(h) ** -2) * sine(domain, freq=freq * label(h)) for h in
+        range(num_harmonics)])
+    wave = np.sum(harmonics, axis=0)
+    return wave