问题
When shell commands are run within a Jupyter Notebook Python Cell, like this:
output = ! some-shell-command
each line emitted to the standard output (stdout) is captured in a list like IPython data-structure called a SList. For instance:
output = !echo -e 'line1\nline2\nline3'
print(output) # A IPython SList data-structure.
['line1', 'line2', 'line3']
Sometimes, however, you want to preserve the original string output format, without tokenization into a list, like this:
print(output)
line1
line2
line3
Example: For structured JSON output -- which is a string containing many newline characters -- you wouldn't want this tokenization to occur.
How, then, can I execute shell commands in Jupyter Notebooks using the ! operator, and retrieve un-tokenized output (like above)?
Ideally, the solution would be something native in Jupyter Notebooks.
Thank you!
回答1:
The SList has a number of properties, that return it in various forms:
https://gist.github.com/parente/b6ee0efe141822dfa18b6feeda0a45e5
In [151]: ret = !ls *.json
In [152]: ret
Out[152]: ['foo1.json', 'foo.json', 'logins.json', 'stack56532806.json']
as list
In [153]: ret.l
Out[153]: ['foo1.json', 'foo.json', 'logins.json', 'stack56532806.json']
as newline separated string:
In [154]: ret.n
Out[154]: 'foo1.json\nfoo.json\nlogins.json\nstack56532806.json'
as space delimited:
In [155]: ret.s
Out[155]: 'foo1.json foo.json logins.json stack56532806.json'
In [156]: type(ret)
its docs
In [158]: ret?
Type: SList
String form: ['foo1.json', 'foo.json', 'logins.json', 'stack56532806.json']
Length: 4
File: /usr/local/lib/python3.6/dist-packages/IPython/utils/text.py
Docstring:
List derivative with a special access attributes.
These are normal lists, but with the special attributes:
* .l (or .list) : value as list (the list itself).
* .n (or .nlstr): value as a string, joined on newlines.
* .s (or .spstr): value as a string, joined on spaces.
* .p (or .paths): list of path objects (requires path.py package)
Any values which require transformations are computed only once and
cached.
回答2:
Use join() to combine an iterator into a string.
"\n".join(output)
来源：https://stackoverflow.com/questions/59973053/jupyter-ipython-slist-obtaining-non-tokenized-output-from-the-shell-execute