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python-gpiozero/gpiozero/tools.py
Andrew Scheller 9fbed050ce Add a new alternating_values SourceTool
2016-09-21 16:16:42 +01:00

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# vim: set fileencoding=utf-8:
from __future__ import (
unicode_literals,
print_function,
absolute_import,
division,
)
str = type('')
from random import random
from time import sleep
try:
from itertools import izip as zip
except ImportError:
pass
from itertools import cycle
from math import sin, cos, pi
try:
from statistics import mean
except ImportError:
from .compat import mean
def negated(values):
"""
Returns the negation of the supplied values (``True`` becomes ``False``,
and ``False`` becomes ``True``). For example::
from gpiozero import Button, LED
from gpiozero.tools import negated
from signal import pause
led = LED(4)
btn = Button(17)
led.source = negated(btn.values)
pause()
"""
for v in values:
yield not v
def inverted(values, input_min=0, input_max=1):
"""
Returns the inversion of the supplied values (*input_min* becomes
*input_max*, *input_max* becomes *input_min*, `input_min + 0.1` becomes
`input_max - 0.1`, etc.). All items in *values* are assumed to be between
*input_min* and *input_max* (which default to 0 and 1 respectively), and
the output will be in the same range. For example::
from gpiozero import MCP3008, PWMLED
from gpiozero.tools import inverted
from signal import pause
led = PWMLED(4)
pot = MCP3008(channel=0)
led.source = inverted(pot.values)
pause()
"""
if input_min >= input_max:
raise ValueError('input_min must be smaller than input_max')
for v in values:
yield input_min + input_max - v
def scaled(values, output_min, output_max, input_min=0, input_max=1):
"""
Returns *values* scaled from *output_min* to *output_max*, assuming that
all items in *values* lie between *input_min* and *input_max* (which
default to 0 and 1 respectively). For example, to control the direction of
a motor (which is represented as a value between -1 and 1) using a
potentiometer (which typically provides values between 0 and 1)::
from gpiozero import Motor, MCP3008
from gpiozero.tools import scaled
from signal import pause
motor = Motor(20, 21)
pot = MCP3008(channel=0)
motor.source = scaled(pot.values, -1, 1)
pause()
.. warning::
If *values* contains elements that lie outside *input_min* to
*input_max* (inclusive) then the function will not produce values that
lie within *output_min* to *output_max* (inclusive).
"""
if input_min >= input_max:
raise ValueError('input_min must be smaller than input_max')
input_size = input_max - input_min
output_size = output_max - output_min
for v in values:
yield (((v - input_min) / input_size) * output_size) + output_min
def clamped(values, output_min=0, output_max=1):
"""
Returns *values* clamped from *output_min* to *output_max*, i.e. any items
less than *output_min* will be returned as *output_min* and any items
larger than *output_max* will be returned as *output_max* (these default to
0 and 1 respectively). For example::
from gpiozero import PWMLED, MCP3008
from gpiozero.tools import clamped
from signal import pause
led = PWMLED(4)
pot = MCP3008(channel=0)
led.source = clamped(pot.values, 0.5, 1.0)
pause()
"""
if output_min >= output_max:
raise ValueError('output_min must be smaller than output_max')
for v in values:
yield min(max(v, output_min), output_max)
def absoluted(values):
"""
Returns *values* with all negative elements negated (so that they're
positive). For example::
from gpiozero import PWMLED, Motor, MCP3008
from gpiozero.tools import absoluted, scaled
from signal import pause
led = PWMLED(4)
motor = Motor(22, 27)
pot = MCP3008(channel=0)
motor.source = scaled(pot.values, -1, 1)
led.source = absoluted(motor.values)
pause()
"""
for v in values:
yield abs(v)
def quantized(values, steps, input_min=0, input_max=1):
"""
Returns *values* quantized to *steps* increments. All items in *values* are
assumed to be between *input_min* and *input_max* (which default to 0 and
1 respectively), and the output will be in the same range.
For example, to quantize values between 0 and 1 to 5 "steps" (0.0, 0.25,
0.5, 0.75, 1.0)::
from gpiozero import PWMLED, MCP3008
from gpiozero.tools import quantized
from signal import pause
led = PWMLED(4)
pot = MCP3008(channel=0)
led.source = quantized(pot.values, 4)
pause()
"""
if steps < 1:
raise ValueError("steps must be 1 or larger")
if input_min >= input_max:
raise ValueError('input_min must be smaller than input_max')
input_size = input_max - input_min
for v in scaled(values, 0, 1, input_min, input_max):
yield ((int(v * steps) / steps) * input_size) + input_min
def booleanized(values, min_value, max_value, hysteresis=0):
"""
Returns True for each item in *values* between *min_value* and
*max_value*, and False otherwise. *hysteresis* can optionally be used to
add `hysteresis`_ which prevents the output value rapidly flipping when
the input value is fluctuating near the *min_value* or *max_value*
thresholds. For example, to light an LED only when a potentiometer is
between 1/4 and 3/4 of its full range::
from gpiozero import LED, MCP3008
from gpiozero.tools import booleanized
from signal import pause
led = LED(4)
pot = MCP3008(channel=0)
led.source = booleanized(pot.values, 0.25, 0.75)
pause()
.. _hysteresis: https://en.wikipedia.org/wiki/Hysteresis
"""
if min_value >= max_value:
raise ValueError('min_value must be smaller than max_value')
min_value = float(min_value)
max_value = float(max_value)
if hysteresis < 0:
raise ValueError("hysteresis must be 0 or larger")
else:
hysteresis = float(hysteresis)
if (max_value - min_value) <= hysteresis:
raise ValueError('The gap between min_value and max_value must be larger than hysteresis')
last_state = None
for v in values:
if v < min_value:
new_state = 'below'
elif v > max_value:
new_state = 'above'
else:
new_state = 'in'
switch = False
if last_state == None or not hysteresis:
switch = True
elif new_state == last_state:
pass
else: # new_state != last_state
if last_state == 'below' and new_state == 'in':
switch = v >= min_value + hysteresis
elif last_state == 'in' and new_state == 'below':
switch = v < min_value - hysteresis
elif last_state == 'in' and new_state == 'above':
switch = v > max_value + hysteresis
elif last_state == 'above' and new_state == 'in':
switch = v <= max_value - hysteresis
else: # above->below or below->above
switch = True
if switch:
last_state = new_state
yield last_state == 'in'
def all_values(*values):
"""
Returns the `logical conjunction`_ of all supplied values (the result is
only ``True`` if and only if all input values are simultaneously ``True``).
One or more *values* can be specified. For example, to light an
:class:`LED` only when *both* buttons are pressed::
from gpiozero import LED, Button
from gpiozero.tools import all_values
from signal import pause
led = LED(4)
btn1 = Button(20)
btn2 = Button(21)
led.source = all_values(btn1.values, btn2.values)
pause()
.. _logical conjunction: https://en.wikipedia.org/wiki/Logical_conjunction
"""
for v in zip(*values):
yield all(v)
def any_values(*values):
"""
Returns the `logical disjunction`_ of all supplied values (the result is
``True`` if any of the input values are currently ``True``). One or more
*values* can be specified. For example, to light an :class:`LED` when
*any* button is pressed::
from gpiozero import LED, Button
from gpiozero.tools import any_values
from signal import pause
led = LED(4)
btn1 = Button(20)
btn2 = Button(21)
led.source = any_values(btn1.values, btn2.values)
pause()
.. _logical disjunction: https://en.wikipedia.org/wiki/Logical_disjunction
"""
for v in zip(*values):
yield any(v)
def averaged(*values):
"""
Returns the mean of all supplied values. One or more *values* can be
specified. For example, to light a :class:`PWMLED` as the average of
several potentiometers connected to an :class:`MCP3008` ADC::
from gpiozero import MCP3008, PWMLED
from gpiozero.tools import averaged
from signal import pause
pot1 = MCP3008(channel=0)
pot2 = MCP3008(channel=1)
pot3 = MCP3008(channel=2)
led = PWMLED(4)
led.source = averaged(pot1.values, pot2.values, pot3.values)
pause()
"""
for v in zip(*values):
yield mean(v)
def summed(*values):
"""
Returns the sum of all supplied values. One or more *values* can be
specified. For example, to light a :class:`PWMLED` as the (scaled) sum of
several potentiometers connected to an :class:`MCP3008` ADC::
from gpiozero import MCP3008, PWMLED
from gpiozero.tools import summed, scaled
from signal import pause
pot1 = MCP3008(channel=0)
pot2 = MCP3008(channel=1)
pot3 = MCP3008(channel=2)
led = PWMLED(4)
led.source = scaled(summed(pot1.values, pot2.values, pot3.values), 0, 1, 0, 3)
pause()
"""
for v in zip(*values):
yield sum(v)
def multiplied(*values):
"""
Returns the product of all supplied values. One or more *values* can be
specified. For example, to light a :class:`PWMLED` as the product (i.e.
multiplication) of several potentiometers connected to an :class:`MCP3008`
ADC::
from gpiozero import MCP3008, PWMLED
from gpiozero.tools import multiplied
from signal import pause
pot1 = MCP3008(channel=0)
pot2 = MCP3008(channel=1)
pot3 = MCP3008(channel=2)
led = PWMLED(4)
led.source = multiplied(pot1.values, pot2.values, pot3.values)
pause()
"""
def _product(it):
p = 1
for n in it:
p *= n
return p
for v in zip(*values):
yield _product(v)
def queued(values, qsize):
"""
Queues up readings from *values* (the number of readings queued is
determined by *qsize*) and begins yielding values only when the queue is
full. For example, to "cascade" values along a sequence of LEDs::
from gpiozero import LEDBoard, Button
from gpiozero.tools import queued
from signal import pause
leds = LEDBoard(5, 6, 13, 19, 26)
btn = Button(17)
for i in range(4):
leds[i].source = queued(leds[i + 1].values, 5)
leds[i].source_delay = 0.01
leds[4].source = btn.values
pause()
"""
if qsize < 1:
raise ValueError("qsize must be 1 or larger")
q = []
it = iter(values)
for i in range(qsize):
q.append(next(it))
for i in cycle(range(qsize)):
yield q[i]
try:
q[i] = next(it)
except StopIteration:
break
def smoothed(values, qsize, average=mean):
"""
Queues up readings from *values* (the number of readings queued is
determined by *qsize*) and begins yielding the *average* of the last
*qsize* values when the queue is full. The larger the *qsize*, the more the
values are smoothed. For example, to smooth the analog values read from an
ADC::
from gpiozero import MCP3008
from gpiozero.tools import smoothed
adc = MCP3008(channel=0)
for value in smoothed(adc.values, 5):
print(value)
"""
if qsize < 1:
raise ValueError("qsize must be 1 or larger")
q = []
it = iter(values)
for i in range(qsize):
q.append(next(it))
for i in cycle(range(qsize)):
yield average(q)
try:
q[i] = next(it)
except StopIteration:
break
def pre_delayed(values, delay):
"""
Waits for *delay* seconds before returning each item from *values*.
"""
if delay < 0:
raise ValueError("delay must be 0 or larger")
for v in values:
sleep(delay)
yield v
def post_delayed(values, delay):
"""
Waits for *delay* seconds after returning each item from *values*.
"""
if delay < 0:
raise ValueError("delay must be 0 or larger")
for v in values:
yield v
sleep(delay)
def pre_periodic_filtered(values, block, repeat_after):
"""
Blocks the first *block* items from *values*, repeating the block after
every *repeat_after* items, if *repeat_after* is non-zero. For example, to
discard the first 50 values read from an ADC::
from gpiozero import MCP3008
from gpiozero.tools import pre_periodic_filtered
adc = MCP3008(channel=0)
for value in pre_periodic_filtered(adc.values, 50, 0):
print(value)
Or to only display every even item read from an ADC::
from gpiozero import MCP3008
from gpiozero.tools import pre_periodic_filtered
adc = MCP3008(channel=0)
for value in pre_periodic_filtered(adc.values, 1, 1):
print(value)
"""
if block < 1:
raise ValueError("block must be 1 or larger")
if repeat_after < 0:
raise ValueError("repeat_after must be 0 or larger")
it = iter(values)
if repeat_after == 0:
for _ in range(block):
next(it)
while True:
yield next(it)
else:
while True:
for _ in range(block):
next(it)
for _ in range(repeat_after):
yield next(it)
def post_periodic_filtered(values, repeat_after, block):
"""
After every *repeat_after* items, blocks the next *block* items from
*values*. Note that unlike :func:`pre_periodic_filtered`, *repeat_after*
can't be 0. For example, to block every tenth item read from an ADC::
from gpiozero import MCP3008
from gpiozero.tools import post_periodic_filtered
adc = MCP3008(channel=0)
for value in post_periodic_filtered(adc.values, 9, 1):
print(value)
"""
if repeat_after < 1:
raise ValueError("repeat_after must be 1 or larger")
if block < 1:
raise ValueError("block must be 1 or larger")
it = iter(values)
while True:
for _ in range(repeat_after):
yield next(it)
for _ in range(block):
next(it)
def random_values():
"""
Provides an infinite source of random values between 0 and 1. For example,
to produce a "flickering candle" effect with an LED::
from gpiozero import PWMLED
from gpiozero.tools import random_values
from signal import pause
led = PWMLED(4)
led.source = random_values()
pause()
If you require a wider range than 0 to 1, see :func:`scaled`.
"""
while True:
yield random()
def sin_values(period=360):
"""
Provides an infinite source of values representing a sine wave (from -1 to
+1) which repeats every *period* values. For example, to produce a "siren"
effect with a couple of LEDs that repeats once a second::
from gpiozero import PWMLED
from gpiozero.tools import sin_values, scaled, inverted
from signal import pause
red = PWMLED(2)
blue = PWMLED(3)
red.source_delay = 0.01
blue.source_delay = red.source_delay
red.source = scaled(sin_values(100), 0, 1, -1, 1)
blue.source = inverted(red.values)
pause()
If you require a different range than -1 to +1, see :func:`scaled`.
"""
angles = (2 * pi * i / period for i in range(period))
for a in cycle(angles):
yield sin(a)
def cos_values(period=360):
"""
Provides an infinite source of values representing a cosine wave (from -1
to +1) which repeats every *period* values. For example, to produce a
"siren" effect with a couple of LEDs that repeats once a second::
from gpiozero import PWMLED
from gpiozero.tools import cos_values, scaled, inverted
from signal import pause
red = PWMLED(2)
blue = PWMLED(3)
red.source_delay = 0.01
blue.source_delay = red.source_delay
red.source = scaled(cos_values(100), 0, 1, -1, 1)
blue.source = inverted(red.values)
pause()
If you require a different range than -1 to +1, see :func:`scaled`.
"""
angles = (2 * pi * i / period for i in range(period))
for a in cycle(angles):
yield cos(a)
def alternating_values(initial_value=False):
"""
Provides an infinite source of values alternating between ``True`` and
``False``, starting wth *initial_value* (which defaults to ``False``). For
example, to produce a flashing LED::
from gpiozero import LED
from gpiozero.tools import alternating_values
from signal import pause
red = LED(2)
red.source_delay = 0.5
red.source = alternating_values()
pause()
"""
value = initial_value
while True:
yield value
value = not value
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