how to set axis interval in candle stick using pyqtgraph with pyqt5? - python-3.x

Question

I am using pyqtgraph to draw a candle stick like the following:
#-------------------
# Create pyqtgraph module
#-------------------
def GUI_DRAW_create():
"""
set default config
"""
pg.setConfigOption('background', 'w') #background: white
pg.setConfigOption('foreground', 'k') #font: black
class TimeAxisItem(pg.AxisItem):
def tickStrings(self, values, scale, spacing):
#values is not my date in timestamp
return [datetime.fromtimestamp(value) for value in values]
## Create a subclass of GraphicsObject.
## The only required methods are paint() and boundingRect()
## (see QGraphicsItem documentation)
class CandlestickItem(pg.GraphicsObject):
def __init__(self, data):
pg.GraphicsObject.__init__(self)
self.data = data ## data must have fields: time, open, close, min, max
self.generatePicture()
def generatePicture(self):
## pre-computing a QPicture object allows paint() to run much more quickly,
## rather than re-drawing the shapes every time.
self.picture = QtGui.QPicture()
p = QtGui.QPainter(self.picture)
p.setPen(pg.mkPen('k'))
w = (self.data[1][0] - self.data[0][0]) / 3.
for (t, open, close, min, max) in self.data:
p.drawLine(QtCore.QPointF(t, min), QtCore.QPointF(t, max))
if open > close:
p.setBrush(pg.mkBrush('r'))
else:
p.setBrush(pg.mkBrush('g'))
p.drawRect(QtCore.QRectF(t-w, open, w*2, close-open))
p.end()
# I try to print out t here, is my date
def paint(self, p, *args):
p.drawPicture(0, 0, self.picture)
def boundingRect(self):
## boundingRect _must_ indicate the entire area that will be drawn on
## or else we will get artifacts and possibly crashing.
## (in this case, QPicture does all the work of computing the bouning rect for us)
return QtCore.QRectF(self.picture.boundingRect())
class GUI_DRAW_new(QMainWindow):
def __init__(self):
super().__init__()
GUI_DRAW_create()
self.setWindowTitle("pyqtgraph example: PlotWidget")
cw = QWidget()
self.setCentralWidget(cw)
main_layout = QHBoxLayout()
cw.setLayout(main_layout)
#variable
self.signalgraph = None
self.data = []
self.vb = None
self.vLine = None
# define plot windows
self.GUI_DRAW_new_graph()
main_layout.addWidget(self.signalgraph)
self.signalgraph.setMouseTracking(True)
self.signalgraph.viewport().installEventFilter(self)
self.show()
def eventFilter(self, source, event):
try:
if (event.type() == QtCore.QEvent.MouseMove and
source is self.signalgraph.viewport()):
pos = event.pos()
print('mouse move: (%d, %d)' % (pos.x(), pos.y()))
if self.signalgraph.sceneBoundingRect().contains(pos):
mousePoint = self.vb.mapSceneToView(pos)
index = int(mousePoint.x())
int(index)
#if index > 0 and index < len(self.data):
#print(self.xdict[index])
# self.label.setHtml("<p style='color:black'>日期：{0}</p>".format(self.data[index]))
# self.label.setPos(mousePoint.x(),mousePoint.y())
self.vLine.setPos(mousePoint.x())
return QtGui.QWidget.eventFilter(self, source, event)
except Exception as e:
traceback.print_exc()
err = sys.exc_info()[1]
PRINT_DEBUG(0,str(err))
def GUI_DRAW_new_graph(self):
try:
self.signalgraph = pg.PlotWidget(name="Signalgraph", axisItems={'bottom': TimeAxisItem(orientation='bottom')})
# sample data
self.data = [ ## fields are (time, open, close, min, max).
(1514995200.0, 102.610001, 105.349998, 102, 105.370003),
(1515081600.0, 105.75, 102.709999, 102.410004, 105.849998),
(1515168000.0, 100.559998, 102.370003, 99.870003, 100.699997),
(1515254400.0, 98.68, 96.449997, 96.43, 100.129997),
(1515340800.0, 98.550003, 96.959999, 96.760002, 99.110001),
(1515427200.0, 102.610001, 105.349998, 102, 105.370003),
(1515513600.0, 105.75, 102.709999, 102.410004, 105.849998),
(1515600000.0, 100.559998, 102.370003, 99.870003, 100.699997),
(1515686400.0, 98.68, 96.449997, 96.43, 100.129997),
(1515772800.0, 98.550003, 96.959999, 96.760002, 99.110001),
]
#if comment this 2 code, can see the string
item = CandlestickItem(self.data)
self.signalgraph.addItem(item)
#trick
s_day = datetime.fromtimestamp(self.data[0][0]).strftime("%Y-%m-%d")
e_day = datetime.fromtimestamp(self.data[len(self.data) - 1][0]).strftime("%Y-%m-%d")
tr=np.arange(s_day, e_day, dtype='datetime64') # tick labels one day
tday0=(tr-tr[0])/(tr[-1]-tr[0]) #Map time to 0.0-1.0 day 2 1.0-2.0 ...
tday1=tday0+1
tnorm=np.concatenate([tday0,tday1])
tr[-1]=tr[0] # End day=start next day
ttick=list()
for i,t in enumerate(np.concatenate([tr,tr])):
tstr=np.datetime64(t).astype(datetime)
ttick.append( (tnorm[i], tstr.strftime("%Y-%m-%d")))
ax=self.signalgraph.getAxis('bottom') #This is the trick
ax.setTicks([ttick])
#cross hair in signalgraph
self.vLine = pg.InfiniteLine(angle=90, movable=False)
self.signalgraph.addItem(self.vLine, ignoreBounds=True)
self.vb = self.signalgraph.plotItem.vb
except Exception as e:
traceback.print_exc()
err = sys.exc_info()[1]
print(0,str(err))
# Start Qt event loop unless running in interactive mode or using pyside.
if __name__ == "__main__":
app = QtGui.QApplication([])
gui = GUI_DRAW_new()
app.exec_()
The result is:
candlestick_graph_center
I want to set the x-axis interval using the date: [2018-01-04, 2018-01-05, 2018-01-06, ....].
Thanks for help, many thanks
Update
I figure out that why all data squeeze together, because of the TextItem.
So that, I rewrite the code.
I try to use tickStrings in AxisItem to convert value to string, when I print out the values in tickStrings, it is not my data value (date in timestamp). Why the values are different? Thanks a lots
Update
If I use setTicks with candle stick, it cannot show string in the graph. Only can show the string without candle stick.
Any idea?

Answer 1

You have to convert into a string with the appropriate format using strftime():
from datetime import datetime
class TimeAxisItem(pg.AxisItem):
def tickStrings(self, values, scale, spacing):
#values is not my date in timestamp
return [datetime.fromtimestamp(value).strftime("%Y-%m-%d") for value in values]
Or:
from datetime import date
class TimeAxisItem(pg.AxisItem):
def tickStrings(self, values, scale, spacing):
#values is not my date in timestamp
return [date.fromtimestamp(value) for value in values]
Or:
from datetime import datetime
class TimeAxisItem(pg.AxisItem):
def tickStrings(self, values, scale, spacing):
#values is not my date in timestamp
return [datetime.fromtimestamp(value).date() for value in values]