Source code for pyqtgraph.widgets.ValueLabel

from ..Qt import QtCore, QtGui
from ..ptime import time
from .. import functions as fn
from functools import reduce

__all__ = ['ValueLabel']

[docs]class ValueLabel(QtGui.QLabel): """ QLabel specifically for displaying numerical values. Extends QLabel adding some extra functionality: - displaying units with si prefix - built-in exponential averaging """
[docs] 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: return fn.siFormat(avg, suffix=self.suffix) else: return self.formatStr.format(value=val, avgValue=avg, suffix=self.suffix)