To setup sam local on an OSX system which is using homebrew.
Check if pip installed.
pip --version
If this returns.
$ pip --version
-bash: pip: command not found
Install python2, as this is currently required by sam-local.
$ brew install python@2
Install sam using pip2
which is the pip used by your homebrew python2 installation.
pip2 install aws-sam-cli
Now run sam.
$ sam --version
SAM CLI, version 0.3.0