[tune] Relative local_dir is not supported.

[pengzhenghao]

System information

• OS Platform and Distribution (e.g., Linux Ubuntu 16.04): macOS Mojave
• Ray installed from (source or binary):
• Ray version:0.7.0.dev2
• Python version:3.6
• Exact command to reproduce:

Describe the problem

If you use

        tune.run(
            self.algo,
            name="TuneRelavtieLocalDirTest",
            stop={"training_iteration": 1},
            checkpoint_freq=1,
            local_dir="ray_result", 
            config={
                "env": "CartPole-v0",
            },
        )

The path of checkpoint turned out to be: $CURRENT_DIR/ray_result/TuneRelavtieLocalDirTest/PG_CartPole-v0_0_2019-05-01_15-24-54xo9z1bq8/ray_result/TuneRelavtieLocalDirTest/PG_CartPole-v0_0_2019-05-01_15-24-54xo9z1bq8/checkpoint_1/checkpoint-1

You can see that the path is nested. It is ought to be $CURRENT_DIR/ray_result/TuneRelavtieLocalDirTest/PG_CartPole-v0_0_2019-05-01_15-24-54xo9z1bq8/checkpoint_1/checkpoint-1

Using local_dir with dot identifier gives the same result.

        tune.run(
            self.algo,
            name="TuneRelavtieLocalDirTest",
            stop={"training_iteration": 1},
            checkpoint_freq=1,
            local_dir="./ray_result", # This should be ray/tune/tests/ray_result
            config={
                "env": "CartPole-v0",
            },
        )

Why this matter? Because in some cases, user needs to take away all the experiments results within their directory of codes, via git or FTP.

---

What about using absolute path?

        abs_path = os.path.abspath("ray_result3")
        print("abs_path:", abs_path) # abs_path: /Users/XXX/ray/python/ray/ray_result3

        tune.run(
            self.algo,
            name="TuneRelavtieLocalDirTest",
            stop={"training_iteration": 1},
            checkpoint_freq=1,
            local_dir=abs_path, # This should be ray/tune/tests/ray_result3
            config={
                "env": "CartPole-v0",
            },
        )

It's correct!

Discussion

I think maybe we can divide the local_dir into three kinds:

1. "./result"
2. "result"
3. "/User/XXX/result"
4. "~/result"

We should consider No.1 & 2 to be the relative path and the last two as absolute path.