Iterating over string in for loop

Question

I have a lot of data files with the following structure,

datafile_1.txt

2.400000000e-01      7.200000000e-01
2.640000000e-01      7.920000000e-01
2.768855359e-01      8.306566078e-01
2.904000000e-01      8.712000000e-01
3.000000000e-01      9.001250000e-01

datafile_2.txt

4.800000000e-01      1.040000000e+00
5.034282471e-01      1.090761202e+00
5.280000000e-01      1.144000000e+00

I have the following code that I use to plot the data,

import numpy  as np
import matplotlib.pyplot as plt
import csv
import os

path = os.path.join(os.path.expanduser('~'), 'Python', 'Simulations', 'DATAFILES', '')
files = ['datafile_1', 'datafile_2']

for file in files:
    with open(path + file + '.txt') as datafile:
        for line in datafile:
            lines = datafile.readlines()
            x0_1  = [float(line.split()[0]) for line in lines]
            y0_1  = [float(line.split()[1]) for line in lines]

            fig = plt.figure() 
            ax1 = fig.add_subplot(111)
            ax1.plot(x0_1, y0_1, 'r', label=file)
            ...
            ...

This code gives me two separate plots --> One for datafile_1.txt and another for datafile_2.txt. But I want the two graphs in the same plot. To do this I wrote these lines,

x0_1 = []
y0_1 = []

for file in files:
    with open(path + file + '.txt') as datafile:
        for line in datafile:
            lines = datafile.readlines()
            x0_1[file]  = [float(line.split()[0]) for line in lines]
            y0_1[file]  = [float(line.split()[1]) for line in lines]

fig = plt.figure() 
ax1 = fig.add_subplot(111)
ax1.plot(x0_1[datafile_1], y0_1[datafile_2], 'r', label=datafile_1)
ax1.plot(x0_1[datafile_2], y0_1[datafile_2], 'g', label=datafile_2)
...
...

I am not sure if this is the right way to do it. But I get an error --> TypeError: list indices must be integers or slices, not str.

So, how do I iterate over the files and store the data as x0_1[datafile_1], y0_1[datafile_1], x0_1[datafile_2], y0_1[datafile_2]?

ax1.plot(x0_1[datafile_1], y0_1[datafile_2], 'r', label=datafile_1) Where are the variables datafile_1 and datafile_2 defined? You probably intend to use a dictionary and access x0_1['datafile_1'] — Ayush
– Ayush, Commented May 26, 2021 at 14:59
Thanks! Exactly what I intended to do. But dicts is new to me so I had no idea about it. — Emotional Damage
– Emotional Damage, Commented May 26, 2021 at 15:06

quamrana · Accepted Answer · 2021-05-26 14:59:25Z

1

I think you meant to make some dicts to hold your data in:

x0_1 = {}
y0_1 = {}

for file in files:
    with open(path + file + '.txt') as datafile:
        for line in datafile:
            lines = datafile.readlines()
            x0_1[file]  = [float(line.split()[0]) for line in lines]
            y0_1[file]  = [float(line.split()[1]) for line in lines]

fig = plt.figure() 
ax1 = fig.add_subplot(111)
ax1.plot(x0_1['datafile_1'], y0_1['datafile_2'], 'r', label='datafile_1')
ax1.plot(x0_1['datafile_2'], y0_1['datafile_2'], 'g', label='datafile_2')

answered May 26, 2021 at 14:59

quamrana

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