experiment-server 0.2

Server for experiments to get configuarations from

Overview

Server for experiments to get configurations from

Setup

Requirements

• Python 3.8+

Installation

Install it directly into an activated virtual environment:

$ pip install experiment-server

or add it to your Poetry project:

$ poetry add experiment-server

Usage

Configuration of an experiment

The configuration id defined in a toml file. See example .toml below for how the configuration can be defined.

# The `configuration` table contains settings of the study itself
[configuration]
# The `order` is an array of block names or an array of array of block names.
order = [["conditionA", "conditionB", "conditionA", "conditionB"]]
# The `groups` and `within_groups` keys allows you to define how the conditions specified
# in `order` will be managed. `groups` would dictate how the top level array of `order`
# will be handled. `within_groups` would dictate how the conditions in the nested arrays
# (if specified) would be managed. These keys can have one of the following values.
# - "latin_square": Apply latin square to balance the values.
# - "randomize": For each participant randomize the order of the values in the array.
# - "as_is": Use the order of the values as specified.
groups = "latin_square"
within_groups= "randomize"

# The subtable `variabels` are values that can be used anywhere when defining the blocks.
# Any variable can be used by appending "$" before the variable name in the blocks. See 
# below for how exmaple of how the variables can be used
[configuration.variables]
TRIALS_PER_ITEM = 3

# Blocks are defined as an array of tables. Each block must contain `name` and the 
# subtable `config`. Optionally, a block can also specify `extends`, whish is a `name` of
# another block. See below for more explanation on how `extends` works

# Block: Condition A
[[blocks]]
name = "conditionA"

# The `config` subtable can have any key-values. Note that `name` and `participant_index`
# will be added to the `config` when this file is being processed. Hence, those keys 
# will be overwritten if used in this subtable.
[blocks.config]
trialsPerItem = "$TRIALS_PER_ITEM"
param1 = 1
param2 = 1
param3 = 1

# Block: Condition B
[[blocks]]
name = "conditionB"
extends = "conditionA"

# Since "conditionB" is extending "conditionA", the keys in the `config` subtable of 
# the block "conditionA" not defined in the `config` subtable of "conditionB" will be copied
# to the `config` subtable of "conditionB". In this example, `param1`, `param2` and 
# `trialsPerItem` will be copied over here.
[blocks.config]
param3 = 2

The above config file would result in the following list of blocks:

[
  {
    "name": "conditionB",
    "extends": "conditionA",
    "config": {
      "param3": 2,
      "trialsPerItem": 3,
      "param1": 1,
      "param2": 1,
      "participant_index": 1,
      "name": "conditionB"
    }
  },
  {
    "name": "conditionB",
    "extends": "conditionA",
    "config": {
      "param3": 2,
      "trialsPerItem": 3,
      "param1": 1,
      "param2": 1,
      "participant_index": 1,
      "name": "conditionB"
    }
  },
  {
    "name": "conditionA",
    "config": {
      "trialsPerItem": 3,
      "param1": 1,
      "param2": 1,
      "param3": 1,
      "participant_index": 1,
      "name": "conditionA"
    }
  },
  {
    "name": "conditionA",
    "config": {
      "trialsPerItem": 3,
      "param1": 1,
      "param2": 1,
      "param3": 1,
      "participant_index": 1,
      "name": "conditionA"
    }
  }
]

Loading experiment through local server

A config file can be validated by running:

$ experiment-server verify-config-file sample_config.toml

This will show how the expanded config looks like for the first 5 participant.

After installation, the server can used as:

$ experiment-server run sample_config.toml

A simple web interface can be accessed at / or /index

The server exposes the following REST API:

• [GET] /itemsCount: The total number of blocks. Returns an integer
• [GET] /active: Test if the server is working. Returns boolean
• [GET] /config: Return the config subtable in the configuration file of the current block as a json object. Note that move_to_next has to be called atleast once before this can be called.
• [GET] /globalData: Returns a json object, with the following keys:
  • "participant_index": the participant index
  • "config_length": same value /itemsCount
• [POST] /move_to_next: Sets the current block to the next block in the list of blocks. Returns a json object, with the key "names", which is the name of the current block after moving. If there are no more blocks, the value of "names" will be "end".
• [POST] /move/:block_id: Set the block at index block_id in the list of blocks as the current block.
• [POST] /shutdown: Shutdown the server.
• [POST] /change_participant_index/:participant_index: Set the participant_index to value participant_index. Note that this will set the sate back to the initial state as if the server was freshly stared.

Loading experiment through API

A configuration can be loaded and managed by importing experiment_server.Experiment.

Wishlist

• Serve multiple participants at the same time.