Hi Patrick,
Exactly what I was looking for – I'd really hoped there was an instruction
like that I was missing .. That's going to make things much easier going
forwards.
Thanks so much :)
On Monday, 28 May 2018 09:34:37 UTC+1, Patrick wrote:
>
> Hi,
>
> You just need to update the image data for the ImageItem (your code keeps
> adding many new ImageItems to the scene!). Change:
>
> img = pg.ImageItem(screen)
> view.addItem(img)
>
> to
>
> img.setImage(screen)
>
> and it will run a lot faster.
>
>
> (Not related to your issue, but ultimately you'd like to put all this in,
> say, an AntDemo class extending a QWidget or similar. Then you can stop
> using global variables which are not the best way to be passing data
> around. But for a simple example like this, globals are easy.)
>
> Patrick
>
> On Sunday, 27 May 2018 12:09:07 UTC+9:30, JSwift2046 wrote:
>>
>> Hi, sorry for such a beginner's question, but I've only been using Python
>> for a couple of weeks, and almost entirely figuring out Keras.
>>
>> But I already love Pyqt, and thanks for developing such a great package.
>> I think this will be a really simple one, but could anyone advise a
>> sensible way to write this?
>>
>> This runs a simple animated Langton's Ant demo, but very slowly, because
>> every update I'm using view.addItem – which is surely not the best way to
>> plot real-time pixels. But very simple to write and look at. Thanks so much
>> – this has been driving me slightly crazy.
>>
>> from PyQt5.QtGui import *
>> from PyQt5.QtCore import *
>> from PyQt5.QtWidgets import *
>> from pyqtgraph.Qt import QtCore, QtGui
>> import numpy as np
>> import pyqtgraph as pg
>> import sys
>>
>> direction = 1
>> x = 250
>> y = 250
>>
>> app = QtGui.QApplication([])
>>
>> w = pg.GraphicsView()
>> w.show()
>> w.resize(500,500)
>> w.setWindowTitle('Ant demo')
>>
>> view = pg.ViewBox()
>> w.setCentralItem(view)
>> view.setAspectLocked(True)
>>
>> screen = np.zeros((500,500))
>> img = pg.ImageItem(screen)
>> view.addItem(img)
>>
>> img.setLevels([0, 1])
>>
>> def update():
>> global screen, img, x, y, direction, w
>>
>> hello = screen[x,y]
>>
>> if hello == 1:
>> direction += 1
>> screen[x,y] = 0
>> else:
>> direction -= 1
>> screen[x,y] = 1
>>
>> if direction == 0:
>> direction = 4
>> if direction == 5:
>> direction = 1
>>
>> if direction == 1:
>> y -= 1
>> elif direction == 2:
>> x += 1
>> elif direction == 3:
>> y += 1
>> elif direction == 4:
>> x -= 1
>>
>> img = pg.ImageItem(screen)
>> view.addItem(img)
>>
>> timer = QtCore.QTimer()
>> timer.timeout.connect(update)
>> timer.start(1)
>>
>> if __name__ == '__main__':
>> import sys
>> if (sys.flags.interactive != 1) or not hasattr(QtCore,
>> 'PYQT_VERSION'):
>> QtGui.QApplication.instance().exec_()
>>
>>
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