pyqtgraph/widgets/ValueLabel.py

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