python join followed by split does not return the original list-CodePudding

Very simply put:

'_'.join(['ACT_X','IEC']).split('_')
# ['ACT', 'X', 'IEC']

From 2 strings that I joined, by the supposedly reverse operation I get 3 strings.

I can see why this is happening, and I get that perhaps the point of join and split is not to handle text that contains the separator itself.
However, in other python code this is correctly handled, e.g. if I write out a csv, and some text contains commas, it is quoted, so the correct columns are read back in.

Can you think of a way to do this (join a list of strings by a separator) so that if any of the joined strings contains the separator, the joined result is fully reversible to the original strings?

In fact I was surprised by the above, because I thought the very point of join was to do something different and more sophisticated than a simple between strings (that is the case in other programming languages).
Now I am wondering what the difference actually is...

CodePudding user response：

Joining them with a character that never appears in the strings is the easiest way out. Depending on your data, suitable characters for this purpose might include "\n", "\t" or "\xf1".

CodePudding user response：

Another solution is to use built-in csv module:

import csv
from io import StringIO

lst = ["ACT_X", "IEC"]

s = StringIO()
writer = csv.writer(s, delimiter="_")
writer.writerow(lst)
s.seek(0)

row = s.read()
print(row)

Prints:

"ACT_X"_IEC

To read it back to list:

reader = csv.reader(StringIO(row), delimiter="_")
print(next(reader))

Prints:

['ACT_X', 'IEC']