Live graph plot from a CSV file with matplotlib

Question

I followed the tutorial on live graph plot from CSV/TXT file, but when I am running the python program no graph is created, instead, the terminal goes into busy mode until I exit using 'Ctrl+Z'.

For some reason, the animate function in matplotlib is not working for me. Instead I wrote the following code, which is supposed to do the job:

import matplotlib.pyplot as plt

while True:
    pullData = open("data1.csv","r").read()
    dataArray = pullData.split('\n')
    xar = []
    yar = []
    for eachLine in dataArray:
        if len(eachLine)>1:
            x,y = eachLine.split(',')
            xar.append(x)
            yar.append(y)
    plt.plot(xar, yar)
    plt.pause(0.05)

plt.show()

But the above code is not reading the data points from the CSV file properly and generating the wrong graph.

I currently have Python 3.6.5 :: Anaconda, Inc. installed on the system. Could someone help in this, please? Thank you in advance.

NobodyInPerson · Accepted Answer · 2019-04-25 20:07:26Z

1

You could use the polt Python package which I developed for this exact purpose of displaying live data.

Supposing you want to display live timeseries of multiple data columns in a CSV file, you could just pipe the live CSV stream (header+live columns) into polt:

(head -n1 myfile.csv; tail -fn0 myfile.csv) | polt add-source -p csv live

Explanation

(
head -n1 myfile.csv; # output first line of CSV file (header) 
tail -fn0 myfile.csv # output new CSV data continuously
) | polt \ # pipe the data into polt
    add-source -p csv # tell polt to interpret data as CSV
    live # do the live plotting

If you do not directly want to plot timeseries, you can check the polt Animator documentation for further displaying possibilities.

answered Apr 25, 2019 at 20:07

NobodyInPerson

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aelgn Over a year ago

Awesome utility!

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