How to find correct character encoding

I am unable to save a buffer due to a character encoding.

I am doing exploratory data analysis using Org babel. Data is read from a file using Python and the results are printed to the buffer.

#+begin_src python :session (concat "*Python: " (file-name-nondirectory (buffer-file-name)) "*") :results output :exports both :tangle yes
dater = r"path\to\data.txt"

with open(dater) as f:

print(line1)
print(line2)
print(line3)
#+end_src

#+RESULTS:
: Freq. V(Vout_2,Vin)
:
: Step Information: Run=0  (Run: 1/513)
:
: 1.00000000000000e+00  (-4.48239687492628e+01dB,1.66628953595615e+02\260)


There is a \260 character at the end of the last line which Emacs complains about:

These default coding systems were tried to encode text
(iso-latin-1-dos (5414 . 4194224))
However, each of them encountered characters it couldn’t encode:
iso-latin-1-dos cannot encode these: \260


I can open the file directly in Emacs and the character renders (see the degree symbol?):

1.00000000000000e+00    (-4.48239687492628e+01dB,1.66628953595615e+02°)
1.04712854805090e+00    (-4.42065188662135e+01dB,1.65176722894121e+02°)


The file encoding that Emacs chooses for the raw file is:

1 -- iso-latin-1-dos (alias: iso-8859-1-dos latin-1-dos)

ISO 2022 based 8-bit encoding for Latin-1 (MIME:ISO-8859-1).
Type: charset (charset)
EOL type: CRLF
This coding system encodes the following charsets:
iso-8859-1


However, regardless of what file encoding I put for the file local variable in the analysis file, Emacs complains when I try to save the analysis buffer.

#+COMMENT: -*- coding: iso-8859-1; -*-


I've tried, utf-8, utf-16, iso-8859-1, iso-8859-15, etc. Basically going down the list of list-coding-systems. I haven't tried all of them yet. But at this point I'm just guessing. To move forward, I'm manually deleting the offending character and saving as utf-8. How can I find an encoding so that I don't need to manually delete results?

• Any idea why the python code block is showing \260 instead of °? – xuchunyang Mar 27 at 15:45
• Good question. I'm not sure why it returns that. – Lorem Ipsum Mar 27 at 15:57