Python - Plotting text file returns 'ValueError: invalid literal for float():'

Question

So I have this text file that i'm trying to plot. It has 5 columns of simulated data and im trying to plot each column from 2 - 5 to the 1st column.

import matplotlib.pyplot as plt
import numpy as np

with open('SampleData.txt') as f:
    data = f.read()
data = data.split('\n')

x = [row.split(' ')[0] for row in data]
y = [row.split(' ')[1] for row in data]

fig = plt.figure()
ax = fig.add_subplot(111)
ax.plot(x,y)
ax.legend()
plt.show()

returning ValueError: could not convert string to float:

Anyway I can fix this?

Thank you

hd1 · Accepted Answer · 2016-05-31 21:23:44Z

3

import matplotlib.pyplot as plt
import numpy as np

with open('SampleData.txt') as f:
    data = f.read()
data = data.split('\n')

x = [float(row.split(' ')[0]) for row in data]
y = [float(row.split(' ')[1]) for row in data]

fig = plt.figure()
ax = fig.add_subplot(111)
ax.plot(x,y)
ax.legend()
plt.show()

It seems that it's a type coercion problem. Let me know if that helps.

answered May 31, 2016 at 21:23

hd1

34.9k5 gold badges83 silver badges95 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

iron2man Over a year ago

Tried it, still returns a 'ValueError'.

iron2man Over a year ago

Sorry you actually helped with my question, the actual error is now ValueError: could not convert string to float: . So i'll see what i can do with that. Thank you.

hd1 Over a year ago

Does your data have a header? If so, eliminate it and read the rest in.

Jiayi Chen · Accepted Answer · 2016-05-31 21:40:11Z

2

The type of the data you obtained from the text file is string. That is to say, before you plot it, you first need to convert it into float type. It can be easily done by float().

x = [float(row.split(' ')[0]) for row in data]
y = [float(row.split(' ')[1]) for row in data]

Make sure that the format of input data is legal for float().

For ValueError: could not convert string to float:, it depends on your text file. There may be some unformatted data in it which cannot be directly converted into float type.

edited May 31, 2016 at 21:40

answered May 31, 2016 at 21:35

Jiayi Chen

445 bronze badges

Comments

Dunnage · Accepted Answer · 2016-05-31 21:24:22Z

0

Try typcasting your split to an integer before using the add_subplot

answered May 31, 2016 at 21:24

Dunnage

997 bronze badges

2 Comments

hd1 Over a year ago

Collectives™ on Stack Overflow

Python - Plotting text file returns 'ValueError: invalid literal for float():'

3 Answers 3

3 Comments

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

3 Comments

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related