Sample project recipe

Open In Colab | Source code

Before you start

Before you start using the Toloka-Kit library in your own Python code, you need to:

Label data

To use Toloka-Kit for data labeling, follow the steps below.

First steps

First, you need to import the necessary libraries into your Python script and set up logging:

import datetime
import time
import logging
import sys
import getpass
import pandas
import toloka.client as toloka
import toloka.client.project.template_builder as tb
format='[%(levelname)s] %(name)s: %(message)s',

Now, create a Toloka client instance. All API calls will go through it:

toloka_client = toloka.TolokaClient(getpass.getpass('Enter your API key: '), 'PRODUCTION') # Or switch to 'SANDBOX'
# Lines below check that the API key is correct and print your account name
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The response to the above request will look like this:

Requester(_unexpected={}, id='6c6c50dce62ca4aef87dfcbc6e9de162', balance=Decimal('1.0000'), public_name={'EN': 'John Smith'}, company=None)


A project is a top-level object. It contains instructions, task interface settings, input and output data specification, and default quality control rules for this project pools. Projects make it easier for you to post similar tasks in the future, because you don't have to re-configure the interface.

The easier the task, the better the results. If your task contains more than one question, you should divide it into several projects.

In this tutorial you will create a project with tasks that ask Tolokers to specify the type of animal depicted in a photo:

new_project = toloka.Project(
public_name='Cat or Dog?',
public_description='Specify the type of animal depicted in a photo.',
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The code above creates an object in your device memory. This is not all, the project must also contain:


Code samples below will add changes to the object stored in your device memory. The data will only be sent to the server after calling one of the toloka_client methods.

Input and output data

The image input field contains URLs of images that need to be labeled.

The result output field will receive cat and dog labels.

input_specification = {'image': toloka.project.UrlSpec()}
output_specification = {'result': toloka.project.StringSpec()}
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The task interface displays the main task elements to Tolokers. It's important because it is how Tolokers see your tasks. If it's too complicated and unclear, the labeling results might be poor.

There are two editors available in Toloka:

Template Builder configures task interface at the entity level. We recommend it for your projects, especially for the first ones.

The code below creates a task interface for our project:

# This component shows images
image_viewer = tb.ImageViewV1(tb.InputData('image'), ratio=[1, 1])
# This component allows to select a label
radio_group_field = tb.RadioGroupFieldV1(
tb.fields.GroupFieldOption('cat', 'Cat'),
tb.fields.GroupFieldOption('dog', 'Dog')
# Allows to set a width limit when displaying a task
task_width_plugin = tb.TolokaPluginV1(
# How Tolokers will see the task
project_interface = toloka.project.TemplateBuilderViewSpec(
view=tb.ListViewV1([image_viewer, radio_group_field]),
# This block assigns task interface and input/output data specification to the project
# Note that this is done via the task specification class
new_project.task_spec = toloka.project.task_spec.TaskSpec(
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The first thing the Tolokers see when they select a task are the instructions that you wrote. Describe what needs to be done in simple and clear language, and give examples.

Good instructions help the Tolokers complete the task correctly. The clarity and completeness of the instructions affect the response quality and the project rating. Unclear or too complex instructions, on the contrary, will scare off Tolokers.

Create the instructions for your project with the following code:

new_project.public_instructions = 'Look at the picture. Determine what is on it: a <b>cat</b> or a <b>dog</b>. Choose the correct option.'

Create project

Now, use toloka_client defined at the beginning to create the project.

The data is only sent to the server after calling one of the toloka_client methods, the code below actually creates a project:

new_project = toloka_client.create_project(new_project)
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You will get an output which looks like this:

[INFO] toloka.client: A new project with ID "120798" has been created. Link to open in web interface:

This means that you successfully created the project with the parameters that you defined at the previous steps.

Preview project

  1. Go to the project page to make sure the task interface works correctly. To do this, click the link in the output of the code above.

  2. In the upper-right corner of the project page click Project actionsPreview Preview:

    What the project interface might look like
  3. In the upper part of the preview page click Change input data, and insert an image URL into the image field, then click Apply:

    What the task interface might look like and how to insert images in the preview
  4. In the upper part of the preview demonstration click Instructions. Make sure the instructions are shown and that they say what you want them to.

  5. Select an option in your task. In the lower-left corner of the preview demonstration click Submit, then View responses. In the appeared result window, check that your results are written in expected format and that the entered data is correct:

    What the results might look like
  • We strongly recommend checking the task interface and instructions every time you create a project. This will help you to ensure that the Tolokers will complete the task and that your results will be useful.

  • Do a trial run with a small amount of data. Make sure that after running the entire pipeline you get the data in the expected format and quality.


A pool is a set of tasks that share common pricing, start date, selection of Tolokers, overlap, and quality control configurations. All task in a pool are processed in parallel. One project can have several pools. You can add new tasks to a pool at any time, as well as open or stop it.

The code below will create a pool as an object in your device memory. You will send it to Toloka with toloka_client method a bit later.

new_pool = toloka.Pool(,
private_name='Pool 1', # Only you can see this information
reward_per_assignment=0.005, # Sets the minimum payment amount for one task suite in USD
assignment_max_duration_seconds=60*5, # Gives Tolokers 5 minutes to complete one task suite
will_expire=datetime.datetime.utcnow() + datetime.timedelta(days=365), # Sets that the pool will close after one year
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To minimize the risk of getting wrong answers, you can ask several Tolokers to complete the same task. This is called overlap.

In this example we set the overlap to 3. This means that every task will be completed by three different Tolokers.

new_pool.defaults = toloka.pool.Pool.Defaults(
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Task suite

A task suite is a set of tasks that are shown on a single page.

An important part of configuring pools is to decide how many tasks will be assigned to a Toloker at once. For example, if you set 3 tasks for a task suite, a Toloker will see three images at once on one page.


The reward_per_assignment and assignment_max_duration_seconds fields in pool settings set the price and time for one task suite, not task.

Why you should combine tasks in a task suite:

  • To set a more precise price for a single task.

  • To calculate a Toloker's skill and use it to determine the correct answer more accurately. Learn more in the Aggregation section.

  • To better apply quality control settings that improve the final quality of the response. Learn more in the Quality control rules section.

real_tasks_count=10, # The number of tasks per page.
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Filters help you select Tolokers for your project.

There may be different reasons to use filters, for example:

  • You require some specific group of Tolokers for your pool.

  • You want to exclude a certain group of Tolokers.

Tasks will only be shown to matching Tolokers, rather than to all of them.

This example requires English-speaking Tolokers, because the project instructions are in English:

new_pool.filter = toloka.filter.Languages.in_('EN')
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Quality control rules

Quality control rules regulate task completion and Toloker access.

Quality control lets you get more accurate responses and restrict access to tasks for cheating users. All rules work independently. Learn more about settting up quality control.

This example uses the captcha rule. It is the simplest way to exclude fake users (robots) and cheaters:

# Turns on captchas
# Bans Tolokers by captcha criteria
# Type of quality control rule
# This condition triggers the action below
# Here overridden comparison operator actually returns a Condition object
conditions=[toloka.conditions.FailRate > 20],
# What exactly should the rule do when the condition is met
# It bans the Toloker for 1 day
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Create pool

The code below creates a pool with all the information above which was stored in your device memory:

new_pool = toloka_client.create_pool(new_pool)
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You will get an output which looks like this:

[INFO] toloka.client: A new pool with ID "36502086" has been created. Link to open in web interface:

Open your project page. You will see your new pool:

Project interface with a pool

The pool interface looks like this:

Pool interface

Right now the pool is empty and closed. It has no tasks or task suites.

Upload tasks

A task is the smallest portion of data you need to mark up.

This example uses a small data set with images. This dataset is collected by the Toloka team and distributed under a Creative Commons Attribution 4.0 International license.

Download the data set

curl --output dataset.tsv

Use the code below to parse the downloaded TSV file:

dataset = pandas.read_csv('dataset.tsv', sep='\t')
print(f'Dataset contains {len(dataset)} rows\n')
dataset = dataset.sample(frac=1).reset_index(drop=True)

Create tasks. One task will be created from one image.

Toloka will automatically create task suites and show the tasks depending on a project overlap:

  1. One task suite will consist of 10 tasks.

  2. Toloka will let 3 different Tolokers to complete the tasks.

We configured these settings while creating the pool.

tasks = [
toloka.Task(input_values={'image': url},
for url in dataset['url']
# Add tasks to a pool
toloka_client.create_tasks(tasks, allow_defaults=True)
print(f'Populated pool with {len(tasks)} tasks')
print(f'To view this pool, go to{}/pool/{}')
# print(f'To view this pool, go to{}/pool/{}') # Print a sandbox version link
# Opens the pool
new_pool = toloka_client.open_pool(
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When you open your pool, Tolokers will see your tasks in their mobile app or in Toloka web version, and start working on them.

In small pools like this, it usually takes up to 10 minutes for all the tasks to be performed.

With big pools, we recommend that you set up automatic waiting. See the example below:

pool_id =
def wait_pool_for_close(pool_id, minutes_to_wait=1):
sleep_time = 60 * minutes_to_wait
pool = toloka_client.get_pool(pool_id)
while not pool.is_closed():
op = toloka_client.get_analytics([toloka.analytics_request.CompletionPercentagePoolAnalytics(])
op = toloka_client.wait_operation(op)
percentage = op.details['value'][0]['result']['value']
f' {"%H:%M:%S")}\t'
f'Pool {} - {percentage}%'
pool = toloka_client.get_pool(
print('Pool was closed.')
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The response to the above request will look like this:

Dataset contains 202 rows
100%|████████████████████████████████████████████| 100/100 [00:23<00:00, 4.34it/s]
Populated pool with 202 tasks
To view this pool, go to
100%|████████████████████████████████████████████| 100/100 [00:01<00:00, 51.91it/s]
19:08:35 Pool 36502086 - 0%
100%|████████████████████████████████████████████| 100/100 [00:00<00:00, 157.34it/s]
19:09:36 Pool 36502086 - 74%
100%|████████████████████████████████████████████| 100/100 [00:01<00:00, 51.10it/s]
19:12:42 Pool 36502086 - 100%
Pool was closed.
[WARNING] toloka.client: Experimental method
answers count: 606

Complete code

The complete code for creating a project, adding a pool, uploading tasks, and starting labeling

Get responses

When all the tasks are completed, look at the responses from Tolokers:

answers_df = toloka_client.get_assignments_df(pool_id)
# Prepare dataframe for aggregation
answers_df = answers_df.rename(columns={
'INPUT:image': 'task',
'OUTPUT:result': 'label',
'ASSIGNMENT:worker_id': 'worker',
print(f'answers count: {len(answers_df)}')
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An assignment value is one Toloker's responses to all the tasks on a task suite.

If a Toloker completed several task suites, then toloka_client.get_assignments_df will contain several assignment values.


You should run the results aggregation only if you set the overlap for the tasks to 2 or higher.

The majority vote method is a quality control method based on matching responses from the majority of Tolokers who complete the same task. For example, if 2 out of 3 Tolokers selected the cat label, then the final label for this task will be cat.

Majority vote is easily implemented, but you can also use our crowdsourcing Crowd-Kit library. It contains a lot of new aggregation methods.

Install it using the command below:

$ pip install crowd-kit

And include it into your script:

from crowdkit.aggregation import MajorityVote
# Run majority vote aggregation
predicted_answers = MajorityVote().fit_predict(answers_df)
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Run the code and look at the results.

The output might look like this:

answers count: 606
task cat cat cat cat cat
... dog dog dog dog dog
Name: agg_label, Length: 202, dtype: object

If you prefer to run the code using Jupyter Notebook, you will have a visual preview for the images from your tasks:

Possible results

Complete code

The complete code for getting results

Last updated: February 7, 2023

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toloka.autoquality [autoquality]