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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.
Team members with view-only seats cannot download artifacts.

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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.
  • During a run
  • Outside of a run
  • W&B CLI
First, import the W&B Python SDK. Next, create a W&B Run:
import wandb

with wandb.init(project="<example>", job_type="<job-type>") as run:
    # See next step
Indicate the artifact you want to use with the wandb.Run.use_artifact() method. This returns a run object. In the following code snippet specifies an artifact called 'bike-dataset' with the alias 'latest':
# Indicate the artifact to use. Format is "name:alias"
artifact = run.use_artifact("bike-dataset:latest")
Use the object returned to download all the contents of the artifact:
# Download the entire 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.Use the wandb.Artifact.get_entry() method to download only a subset of files:
# Download a specific file
entry = artifact.get_entry(name)
Putting this together, the complete code example looks like this:
import wandb    

with wandb.init(project="<example>", job_type="<job-type>") as run:
    # Indicate the artifact to use. Format is "name:alias"
    artifact = run.use_artifact("bike-dataset:latest")

    # Download the entire artifact
    datadir = artifact.download()

    # Download a specific file
    entry = artifact.get_entry("bike.png")
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

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Partially download an artifact

You can optionally download part of an artifact based on a prefix. Use the path_prefix= (wandb.Artifact.download(path_prefix=)) parameter to download a single file or the content of a sub-folder. 
with wandb.init(project="<example>", job_type="<job-type>") as run:
    # Indicate the artifact to use. Format is "name:alias"
    artifact = run.use_artifact("bike-dataset:latest")

    # Download a specific file or sub-folder
    artifact.download(path_prefix="bike.png") # downloads only bike.png
Alternatively, you can download files from a certain directory. To do so, specify the directory within the path_prefix= parameter. Continuing from the previous code snippet: 
# downloads files in the images/bikes directory
artifact.download(path_prefix="images/bikes/")

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

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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 wandb.Run.use_artifact() API is idempotent, so you can call it as many times as you like. 
import wandb

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