Source code for pyqtgraph.widgets.ValueLabel

# -*- coding: utf-8 -*-
from time import perf_counter
from ..Qt import QtGui
from .. import functions as fn

__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 = perf_counter() 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 sum(v[1] for v in self.values) / float(len(self.values)) def paintEvent(self, ev): self.setText(self.generateText()) return super().paintEvent(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)