I had the same problem. My solution:

Run from terminal to install pyls:
pip install 'python-language-server[all]'

Print out details of WHERE the python language server was installed:
pip show python-language-server

Which gave me the path:

Location: /home/bad/.local/lib/python3.7/site-packages

I browsed to that path and found the 'pyls' folder. Then I went into atom and edited the configuration to point at '/home/bad/.local/lib/python2.7/site-packages/pyls'. Specifically, if I go into EDIT>CONFIG in the Atom menu I have this:
: "atom-ide-ui": use: {} core: telemetryConsent: "no" "exception-reporting": userId: "30865088-5ba0-4a4b-bfd9-04fa28903321" "ide-python": pylsPath: "/home/bad/.local/lib/python2.7/site-packages/pyls"

出　　处：https://www.cnblogs.com/dnrops/p/13767127.html