ValueError: could not convert string to float:

Question

I have a problem with the following code:

inputf = open('test.dat', 'r')
lines = inputf.readlines()
rico_clus_e = []
for line in lines:
    line.split()
    print line
    if (line[0] != '#'):
        rico_clus_e.append(float(line[4]))
inputf.close()

My test.dat file is:

# specn rico_all        rico_all_e  rico_clus   rico_clus_e rico_farclust   rico_far_e  extin
a119        1.07038692  0.11109547  0.61473431  0.15063627  0.32590239      0.14777812  0.207

And this gives the following output in my terminal:

# specn rico_all        rico_all_e  rico_clus   rico_clus_e rico_farclust   rico_far_e  extin

a119        1.07038692  0.11109547  0.61473431  0.15063627  0.32590239      0.14777812  0.207

Traceback (most recent call last):
  File "test.py", line 8, in <module>
    rico_clus_e.append(float(line[4]))
ValueError: could not convert string to float:

I'm quite confused by this. It had nothing to do with spaces, I checked them all. And if you change 4 by 1, 2 or 3 this works, so it must have something to do with the test.dat file, but I can't seem to figure out how. I'm using python 2.7.3.

The representation (hint: repr()) of the element is...?

Ignacio Vazquez-Abrams
– Ignacio Vazquez-Abrams

2013-06-03 20:44:28 +00:00
Commented Jun 3, 2013 at 20:44 — Ignacio Vazquez-Abrams
– Ignacio Vazquez-Abrams, Commented Jun 3, 2013 at 20:44
The representation is ' '

Janos Braem
– Janos Braem

2013-06-03 20:52:02 +00:00
Commented Jun 3, 2013 at 20:52 — Janos Braem
– Janos Braem, Commented Jun 3, 2013 at 20:52

Ignacio Vazquez-Abrams · Accepted Answer · 2013-06-03 21:00:06Z

1

line.split() on its own does nothing to line. You must store the result of the method call and use that instead.

answered Jun 3, 2013 at 21:00

Ignacio Vazquez-Abrams

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3 Comments

Janos Braem Over a year ago

But why does it work for the other values? Changing 4 to 3, 2 or 1 does work... For number 3, the representation is '9', for element 2 it's '1'

Ignacio Vazquez-Abrams Over a year ago

That's because line[3] is '9', and line[2] is '1'. And line[0] is 'a'.

Janos Braem Over a year ago

Okay, I understand your response now. It thought that '9' was something internal, but it just refers to the string. line = line.split() is the thing that did the trick. Thx!

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