Download and use artifacts

Download and use an artifact that is already stored on the W&B server or construct an artifact object and pass it in to for de-duplication as necessary.

note

Team members with view-only seats cannot download artifacts.

Download and use an artifact stored on W&B

Download and use an artifact stored in W&B either inside or outside of a W&B Run. Use the Public API (wandb.Api) to export (or update data) already saved in W&B. For more information, see the W&B Public API Reference guide.

During a run

First, import the W&B Python SDK. Next, create a W&B Run:

import wandb

run = wandb.init(project="<example>", job_type="<job-type>")

Indicate the artifact you want to use with the use_artifact method. This returns a run object. In the proceeding code snippet specifies an artifact called 'bike-dataset' with the alias 'latest':

artifact = run.use_artifact("bike-dataset:latest")

Use the object returned to download all the contents of the artifact:

datadir = artifact.download()

You can optionally pass a path to the root parameter to download the contents of the artifact to a specific directory. For more information, see the Python SDK Reference Guide.

Use the get_path method to download only subset of files:

path = artifact.get_path(name)

This fetches only the file at the path name. It returns an Entry object with the following methods:

• Entry.download: Downloads file from the artifact at path name
• Entry.ref: If add_reference stored the entry as a reference, returns the URI

References that have schemes that W&B knows how to handle get downloaded just like artifact files. For more information, see Track external files.

Outside of a run

First, import the W&B SDK. Next, create an artifact from the Public API Class. Provide the entity, project, artifact, and alias associated with that artifact:

import wandb

api = wandb.Api()
artifact = api.artifact("entity/project/artifact:alias")

Use the object returned to download the contents of the artifact:

artifact.download()

You can optionally pass a path the root parameter to download the contents of the artifact to a specific directory. For more information, see the API Reference Guide.

W&B CLI

Use the wandb artifact get command to download an artifact from the W&B server.

$ wandb artifact get project/artifact:alias --root mnist/

Partially download an artifact

You can optionally download part of an artifact based on a prefix. Using the path_prefix parameter, you can download a single file or the content of a sub-folder.

artifact = run.use_artifact("bike-dataset:latest")

artifact.download(path_prefix="bike.png") # downloads only bike.png

Alternatively, you can download files from a certain directory:

artifact.download(path_prefix="images/bikes/") # downloads files in the images/bikes directory

Use an artifact from a different project

Specify the name of artifact along with its project name to reference an artifact. You can also reference artifacts across entities by specifying the name of the artifact with its entity name.

The following code example demonstrates how to query an artifact from another project as input to the current W&B run.

import wandb

run = wandb.init(project="<example>", job_type="<job-type>")
# Query W&B for an artifact from another project and mark it
# as an input to this run.
artifact = run.use_artifact("my-project/artifact:alias")

# Use an artifact from another entity and mark it as an input
# to this run.
artifact = run.use_artifact("my-entity/my-project/artifact:alias")

Construct and use an artifact simultaneously

Simultaneously construct and use an artifact. Create an artifact object and pass it to use_artifact. This creates an artifact in W&B if it does not exist yet. The use_artifact API is idempotent, so you can call it as many times as you like.

import wandb

artifact = wandb.Artifact("reference model")
artifact.add_file("model.h5")
run.use_artifact(artifact)

For more information about constructing an artifact, see Construct an artifact.