Retrieve imported data in the labeling configuration

In order to get data into tasks, you have to import it. Then you have to specify how you want to retrieve that data to use it in a task. This is done with object tags.

An object tag is a type of tag that indicates what data you are retrieving. Label Studio has the following object tags:

• Audio
• HyperText (HTML)
• Image
• List
• Paragraphs
• Table
• Text
• TimeSeries
• Video

Use the following parameters in the object tag.

value (required)

The value parameter represents the source of the data. It can be plain text or a step of complex data retrieval system.

Variables

This is the most common way to specify the value and dynamically populates data. Variables are prefixed with a $.

For example, <Audio value="$audio" ... /> seeks the “audio” field in the imported JSON object:

{
  "data": {
    "audio": "https://host.name/myaudio.wav"
  }
}

Hardcoded string

The value parameter can also be a string, this is particularly useful for Header and Text.

You can use the content of the tag as the value. This is useful for descriptive text tags and is applied for Label and Choice.

For example:

<Header>Label audio:</Header>
<Header value="Label only fully visible cars" />
<Text name="instruction" value="Label only fully visible cars" />

<Label>cat</Label>
<Choice>other</Choice>

Other cases

The value parameter can be text containing variables:

For example:

<Header value="url: $image"/>

The value parameter can also refer to nested data in arrays and dicts ($texts[2] and $audio.url).

For example:

<Image name="image" value="$images[0]"/>

valueType (optional)

The valueType parameter defines how to treat the data retrieved from the previous steps and whether it should be retrieved from uploaded data or from a URL.

For example:

• Using “url”: <Text name="text1" value="$text" valueType="url"/> displays the text loaded by the URL.

• Using “text”: <Text name="text" value="$text" valueType="text"/> displays the URL without loading the text.

resolver (optional)

Use this parameter to retrieve data from multi-column CSV on S3 or other cloud storage. Label Studio can retrieve it only in run-time, so it’s secure.

If you import a file with a list of tasks, and every task in this list is a link to another file in the storage. In this case, you can use the resolver parameter to retrieve the content of these files from a storage.

Use case

There is a list of tasks, where the “remote” field of every task is a link to a CSV file in the storage. Every CSV file has a “text” column with text to be labeled. For example:

Tasks:

[
    { "remote": "s3://bucket/text1.csv" },
    { "remote": "s3://bucket/text2.csv" }
]

CSV file:

id;text
12;The most flexible data annotation tool. Quickly installable. Build custom UIs or use pre-built labeling templates.

Solution

To retrieve the file, use the following parameters:

1. value="$remote": The URL to CSV on S3 is in “remote” field of task data. If you use the resolver parameter the value is always treated as URL, so you don’t need to set valueType.

2. resolver="csv|separator=;|column=text": Load this file in run-time, parse it as CSV, and get the “text” column from the first row.

3. Display the result.

Syntax

The syntax for the resolver parameter consists of a list of options separated by a | symbol.

The first option is the type of file.

The remaining options are parameters of the specified file type with optional values. The parameters for CSV files are:

• headless: A CSV file does not have headers (this parameter is boolean and can’t have a value).
• separator=;: CSV separator, usually can be detected automatically.
• column=1: In headless mode use zero-based index, otherwise use column name.

For example, resolver="csv|headless|separator=;|column=1"