# %% [markdown]

# A tutorial on how to list and download tasks.

# %%

import openml

from openml.tasks import TaskType

# %% [markdown]

#

# Tasks are identified by IDs and can be accessed in two different ways:

#

# 1. In a list providing basic information on all tasks available on OpenML.

# This function will not download the actual tasks, but will instead download

# meta data that can be used to filter the tasks and retrieve a set of IDs.

# We can filter this list, for example, we can only list tasks having a

# special tag or only tasks for a specific target such as

# *supervised classification*.

# 2. A single task by its ID. It contains all meta information, the target

# metric, the splits and an iterator which can be used to access the

# splits in a useful manner.

# %% [markdown]

# ## Listing tasks

#

# We will start by simply listing only *supervised classification* tasks.

#

# **openml.tasks.list_tasks()** returns a dictionary of dictionaries by default, but we

# request a

# [pandas dataframe](https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.html)

# instead to have better visualization capabilities and easier access:

# %%

tasks = openml.tasks.list_tasks(task_type=TaskType.SUPERVISED_CLASSIFICATION)

print(tasks.columns)

print(f"First 5 of {len(tasks)} tasks:")

print(tasks.head())

# %% [markdown]

# We can filter the list of tasks to only contain datasets with more than

# 500 samples, but less than 1000 samples:

# %%

filtered_tasks = tasks.query("NumberOfInstances > 500 and NumberOfInstances < 1000")

print(list(filtered_tasks.index))

# %%

# Number of tasks

print(len(filtered_tasks))

# %% [markdown]

# Then, we can further restrict the tasks to all have the same resampling strategy:

# %%

filtered_tasks = filtered_tasks.query('estimation_procedure == "10-fold Crossvalidation"')

print(list(filtered_tasks.index))

# %%

# Number of tasks

print(len(filtered_tasks))

# %% [markdown]

# Resampling strategies can be found on the

# [OpenML Website](https://www.openml.org/search?type=measure&q=estimation%20procedure).

#

# Similar to listing tasks by task type, we can list tasks by tags:

# %%

tasks = openml.tasks.list_tasks(tag="OpenML100")

print(f"First 5 of {len(tasks)} tasks:")

print(tasks.head())

# %% [markdown]

# Furthermore, we can list tasks based on the dataset id:

# %%

tasks = openml.tasks.list_tasks(data_id=1471)

print(f"First 5 of {len(tasks)} tasks:")

print(tasks.head())

# %% [markdown]

# In addition, a size limit and an offset can be applied both separately and simultaneously:

# %%

tasks = openml.tasks.list_tasks(size=10, offset=50)

print(tasks)

# %% [markdown]

#

# **OpenML 100**

# is a curated list of 100 tasks to start using OpenML. They are all

# supervised classification tasks with more than 500 instances and less than 50000

# instances per task. To make things easier, the tasks do not contain highly

# unbalanced data and sparse data. However, the tasks include missing values and

# categorical features. You can find out more about the *OpenML 100* on

# [the OpenML benchmarking page](https://docs.openml.org/benchmark/).

#

# Finally, it is also possible to list all tasks on OpenML with:

# %%

tasks = openml.tasks.list_tasks()

print(len(tasks))

# %% [markdown]

# ## Exercise

#

# Search for the tasks on the 'eeg-eye-state' dataset.

# %%

tasks.query('name=="eeg-eye-state"')

# %% [markdown]

# ## Downloading tasks

#

# We provide two functions to download tasks, one which downloads only a

# single task by its ID, and one which takes a list of IDs and downloads

# all of these tasks:

# %%

task_id = 31

task = openml.tasks.get_task(task_id)

# %%

# Properties of the task are stored as member variables:

print(task)

# %%

# And:

ids = [2, 1891, 31, 9983]

tasks = openml.tasks.get_tasks(ids)

print(tasks[0])

# %% [markdown]

# ## Creating tasks

#

# You can also create new tasks. Take the following into account:

#

# * You can only create tasks on *active* datasets

# * For now, only the following tasks are supported: classification, regression,

# clustering, and learning curve analysis.

# * For now, tasks can only be created on a single dataset.

# * The exact same task must not already exist.

#

# Creating a task requires the following input:

#

# * task_type: The task type ID, required (see below). Required.

# * dataset_id: The dataset ID. Required.

# * target_name: The name of the attribute you aim to predict. Optional.

# * estimation_procedure_id : The ID of the estimation procedure used to create train-test

# splits. Optional.

# * evaluation_measure: The name of the evaluation measure. Optional.

# * Any additional inputs for specific tasks

#

# It is best to leave the evaluation measure open if there is no strong prerequisite for a

# specific measure. OpenML will always compute all appropriate measures and you can filter

# or sort results on your favourite measure afterwards. Only add an evaluation measure if

# necessary (e.g. when other measure make no sense), since it will create a new task, which

# scatters results across tasks.

# %% [markdown]

# We'll use the test server for the rest of this tutorial.

# %%

openml.config.start_using_configuration_for_example()

# %% [markdown]

# ## Example

#

# Let's create a classification task on a dataset. In this example we will do this on the

# Iris dataset (ID=128 (on test server)). We'll use 10-fold cross-validation (ID=1),

# and *predictive accuracy* as the predefined measure (this can also be left open).

# If a task with these parameters exists, we will get an appropriate exception.

# If such a task doesn't exist, a task will be created and the corresponding task_id

# will be returned.

# %%

try:

my_task = openml.tasks.create_task(

task_type=TaskType.SUPERVISED_CLASSIFICATION,

dataset_id=128,

target_name="class",

evaluation_measure="predictive_accuracy",

estimation_procedure_id=1,

)

my_task.publish()

except openml.exceptions.OpenMLServerException as e:

# Error code for 'task already exists'

if e.code == 614:

# Lookup task

tasks = openml.tasks.list_tasks(data_id=128)

tasks = tasks.query(

'task_type == "Supervised Classification" '

'and estimation_procedure == "10-fold Crossvalidation" '

'and evaluation_measures == "predictive_accuracy"'

)

task_id = tasks.loc[:, "tid"].values[0]

print("Task already exists. Task ID is", task_id)

# %%

openml.config.stop_using_configuration_for_example()