Python字符串串联和等效的bash参数扩展

Question

I'm kind of new to python, but something I find myself doing in bash a lot is prepending and appending strings to filenames with parameter expansion.

eg

for file in *.txt ; do mkdir ${file%.*} ; mv $file ${file%.*}/ ; done

Would be an example for stripping off the extension of a load of files, making directories based on those names, and then moving the files inside their namesake folders now.

If I want to achieve a similar thing, such as rename the output of a function based on the input file name (below is an example of a Biopython function), I've seen a few ways to do it with string concatenation etc, but without bracketing and so on, it looks confusing and like it might create parsing errors with spaces, quotes and so on being all over the place potentially.

SeqIO.convert(genbank, 'genbank', genbank[:-3]+'tmp', 'fasta')

There are other threads on here about using rsplit, string concatenation and so on, but is one of these more 'correct' than another?

String concatenation is really nice and works great in simple commands like print() , but when adding to commands that are expecting separated values, it strikes me as a little messy?

Answer 1

You can use os.path.splitext which is build especially for file names:

>>> import os
>>> 
>>> fname = '/tmp/foo/bar.baz'
>>> sp = os.path.splitext(fname)
>>> sp
('/tmp/foo/bar', '.baz')

Extracting the name of the file without extension:

>>> os.path.basename(sp[0])
'bar'

And formatting a new file name:

>>> "{}.txt".format(os.path.basename(sp[0]))
'bar.txt'

In general, when manipulating file names and paths I try to just use os.path , since it already handles edge cases, can normalize paths from things like /..//./././ , etc.