Data will not plot

[Chamath Vithanawasam]

Hey,

I recently got to know about pyqtgraph and I simply love it. I am making a project that involves taking 20 readings from a GPIO and then plotting then on a graph. This needs to happen repeatedly. I used fragments from the example code plotting.py given in the examples folder and the code used to collect GPIO data. It is shown below.

import time
import os

import Adafruit_GPIO.SPI as SPI
import Adafruit_MCP3008

import RPi.GPIO as GPIO
import time
from time import sleep


##BELOW ARE STUFF ASSOCIATED WITH THE PLOTTING


import initExample ## Add path to library (just for examples; you do not need this)


from pyqtgraph.Qt import QtGui, QtCore
import numpy as np
import pyqtgraph as pg


#-------------------------------------------#


# Software SPI configuration:
#CLK  = 18
#MISO = 23
#MOSI = 24
#CS   = 25
#mcp = Adafruit_MCP3008.MCP3008(clk=CLK, cs=CS, miso=MISO, mosi=MOSI)


# Hardware SPI configuration:
SPI_PORT   = 0
SPI_DEVICE = 0
mcp = Adafruit_MCP3008.MCP3008(spi=SPI.SpiDev(SPI_PORT, SPI_DEVICE))


#QtGui.QApplication.setGraphicsSystem('raster')
app = QtGui.QApplication([])
#mw = QtGui.QMainWindow()
#mw.resize(800,800)


#-------------------------------------------#


win = pg.GraphicsWindow(title="Basic plotting examples")
win.resize(1000,600)
win.setWindowTitle('pyqtgraph example: Plotting')


# Enable antialiasing for prettier plots
pg.setConfigOptions(antialias=True)


newArray = []


for x in range(20):
    values = [0]*8
    #for i in range(8):
    #The read_adc function will get the value of the specified channel (0-7).
    values[0] = mcp.read_adc(0)
    # Print the ADC values.
   
    print('Current value is')
    print(values[0])
   
    newArray.append([values[0]])
    print(newArray)
   
    time.sleep(0.5)


##ranArray = np.random
ranArray = np.asarray(newArray)
print(ranArray)


p6 = win.addPlot(title="S11")
curve = p6.plot(pen='w')
data = np.asarray(newArray)


##.normal(size=(20,20))


ptr = 0
def update():
    global curve, data, ptr, p6
    curve.setData(data[ptr%10])
    if ptr == 0:
        p6.enableAutoRange('xy', False)  ## stop auto-scaling after the first data set is plotted
    ptr += 1
    print(data)
timer = QtCore.QTimer()
timer.timeout.connect(update)
timer.start(1000) #1000 = 1 second


## Start Qt event loop unless running in interactive mode or using pyside.
if __name__ == '__main__':    
    import sys
    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
        QtGui.QApplication.instance().exec_()

This code will show the data getting appended into an array, but then show a blank graph.

I think it has to do with the data type that is plotted?