Question

我有一个Arduino草图，它将时间，温度值放入loggedData.dat文件中。只需使用Arduino串行监视器查看文件就可以了。但是当我尝试使用下面的python脚本用它绘制图形时，我得到一个错误：

File "loggedData.py", line 44, in <module>
x.append(Float(p[0])) ValueError: could not convert string to float:

如果我只是通过手动输入与原始文件完全相同的值来创建名为loggedData.dat的文件，例如：

1.00, 71.3

2.00, 71.6

3.00, 71.7

4.00, 71.8

工作正常，我得到了一个很好的图表。显然有一些东西进入loggedData.dat文件，我无法使用串行监视器看到。有什么建议吗？

import sys, serial, time
from matplotlib import pyplot as plt
serPort   = '/dev/ttyS1'
dataFile  = open( "./loggedData.dat", "w" );

print "\nAttempting to open Serial Port : ", serPort, "for logging\n"

ser       = serial.Serial( serPort, 9600 )
if ( ser.isOpen() == False ):
    print "ERROR: Unable to open serial port ", serPort, "\n"
    exit(0);
else:
    print "Port ", serPort, " opened\n"

sys.stdout.flush()
print "Hit return to start logging ..."
key = sys.stdin.readline()
ser.write('1');
print "Logging started. CTRL-C to stop\n"
while True:
    try:
        line = ser.readline()
        print line;
        dataFile.write( line )

    except KeyboardInterrupt:                    # CTRL-C triggered here
        ser.write( '0' )
        print "Logging Stopped\n"
        break;

ser.flush()
ser.close()
dataFile.close()
print "Port ", serPort, " closed\n"
print "\nPlot graph (y/n) ?"
key = sys.stdin.read(1)

if key == 'y':
    print "\nPlotting graph ...\n"
    f     = open( "loggedData.dat", 'r' )
    lines = f.readlines()
    f.close()
    x = []
    y = []
    for line in lines:
        p = line.split( ',' )
        x.append( float( p[0] ) )
        y.append( float( p[1] ) )

    fig   = plt.figure()
    graph = fig.add_subplot(111)
    graph.set_title( "Data logged from Arduino UNO" )
    graph.plot( x, y, 'ro' )
    plt.show()

    print "Plot complete\n"
else:
    print "Finishing\n"

time.sleep(3)

Answer 1

如果ctrl字符卡在你的变量上 - 你可以尝试

x.append(Float(p[0].strip()))

获取ValueError试图绘制图形

1 个答案: