how to extract speciific columns from a csv file and plot using python

Question

I have a csv file that contains the following few lines of data:

# Vertex        X                Y                Z               K_I             K_II             K_III              J
  0       2.100000e+00      2.000000e+00     -1.000000e-04    0.000000e+00   0.000000e+00        0.000000e+00    0.000000e+00    
  1       2.100000e+00      2.000000e+00      1.699733e-01    8.727065e+00  -8.696262e-04        -1.800691e-04   3.465355e-04    
  2       2.100000e+00      2.000000e+00      3.367067e-01    8.907810e+00  -2.548819e-04        -2.789738e-04   3.610383e-04

I would like to plot:

vertex (first column) versus K_I (5th column)

vertex (first column) versus K_II (6th column)

vertex (first column) versus K_III (7th column)

How do I extract the specific columns from this file and then plot a line graph from the columns? Any help is greatly appreciated!

TimothyAWiseman · Accepted Answer · 2012-07-21 00:10:21Z

2

To get you started you can look up the CSV library which is made to handle CSVs (as well as tab and other delimited files. There are a couple of options to plot the data, but matplotlib is an excellent option you may want to look at.

And while not exactly what you want, one of my articles on plotting from SQL Server using matplotlib and PyQT was just published that includes some relevant examples of plotting in matplotlib with a PyQT Gui. I don't address pulling the data from a CSV there, though.

answered Jul 21, 2012 at 0:10

TimothyAWiseman

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Burhan Khalid · Accepted Answer · 2012-07-21 03:58:54Z

1

pandas has built-in visualization support which makes this task very simple. It is a lot more straight forward than csv + matplotlib since pandas abstracts that for you.

answered Jul 21, 2012 at 3:58

Burhan Khalid

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Chang She · Accepted Answer · 2012-07-21 06:43:59Z

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import pandas as pd
frame = pd.read_csv('filename.csv', index_col=0)
frame.K_I.plot() # Vertex is the x-axis

also "frame.plot()" plots all columns

answered Jul 21, 2012 at 6:43

Chang She

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user1539217 Over a year ago

I got an error message that says: AttributeError: 'DataFrame' object has no attribute 'K_I'

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