67 lines
2.6 KiB
Python
67 lines
2.6 KiB
Python
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from pyqtgraph.Qt import QtCore, QtGui
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from pyqtgraph.ptime import time
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import pyqtgraph as pg
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__all__ = ['ValueLabel']
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class ValueLabel(QtGui.QLabel):
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"""
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QLabel specifically for displaying numerical values.
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Extends QLabel adding some extra functionality:
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- displaying units with si prefix
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- built-in exponential averaging
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"""
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def __init__(self, parent=None, suffix='', siPrefix=False, averageTime=0, formatStr=None):
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"""
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Arguments:
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*suffix* (str or None) The suffix to place after the value
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*siPrefix* (bool) Whether to add an SI prefix to the units and display a scaled value
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*averageTime* (float) The length of time in seconds to average values. If this value
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is 0, then no averaging is performed. As this value increases
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the display value will appear to change more slowly and smoothly.
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*formatStr* (str) Optionally, provide a format string to use when displaying text. The text will
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be generated by calling formatStr.format(value=, avgValue=, suffix=)
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(see Python documentation on str.format)
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This option is not compatible with siPrefix
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"""
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QtGui.QLabel.__init__(self, parent)
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self.values = []
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self.averageTime = averageTime ## no averaging by default
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self.suffix = suffix
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self.siPrefix = siPrefix
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if formatStr is None:
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formatStr = '{avgValue:0.2g} {suffix}'
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self.formatStr = formatStr
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def setValue(self, value):
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now = time()
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self.values.append((now, value))
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cutoff = now - self.averageTime
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while len(self.values) > 0 and self.values[0][0] < cutoff:
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self.values.pop(0)
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self.update()
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def setFormatStr(self, text):
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self.formatStr = text
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self.update()
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def averageValue(self):
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return reduce(lambda a,b: a+b, [v[1] for v in self.values]) / float(len(self.values))
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def paintEvent(self, ev):
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self.setText(self.generateText())
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return QtGui.QLabel.paintEvent(self, ev)
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def generateText(self):
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if len(self.values) == 0:
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return ''
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avg = self.averageValue()
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val = self.values[-1][1]
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if self.siPrefix:
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return pg.siFormat(avg, suffix=self.suffix)
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else:
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return self.formatStr.format(value=val, avgValue=avg, suffix=self.suffix)
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