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Keyboard functions

class keyboard

The keyboard class is used to collect keyboard responses.

Example:

# Wait for a 'z' or 'x' key with a timeout of 3000 ms
my_keyboard = keyboard(keylist=['z', 'x'], timeout=3000)
start_time = clock.time()
key, end_time = my_keyboard.get_key()
var.response = key
var.response_time = end_time - start_time

Things to know

Key names

  • Key names may differ between backends.
  • Keys can be identified either by character or name, and are case-insentive. For example:
  • The key 'a' is represented by 'a' and 'A'
  • The up arrow is represented by 'up' and 'UP'
  • The '/' key is represented by '/', 'slash', and 'SLASH'
  • The spacebar is represented by 'space' and 'SPACE'
  • To find out the name of key, you can:
  • Click on the 'list available keys' button of the keyboard_response item.
  • Collect a key press with a keyboard_response item, and display the key name through a feedback item with the text 'You pressed [response]' in it.

Response keywords

Functions that accept **resp_args take the following keyword arguments:

  • timeout specifies a timeout value in milliseconds, or is set to None to disable the timeout.
  • keylist specifies a list of keys that are accepted, or is set to None accept all keys.
# Get a left or right arrow press with a timeout of 3000 ms
my_keyboard = keyboard()
key, time = my_keyboard.get_key(keylist=[u'left', u'right'],
        timeout=3000)

Response keywords only affect the current operation (except when passed to keyboard.__init__). To change the behavior for all subsequent operations, set the response properties directly:

# Get two key A or B presses with a 5000 ms timeout
my_keyboard = keyboard()
my_keyboard.keylist = [u'a', u'b']
my_keyboard.timeout = 5000
key1, time1 = my_keyboard.get_key()
key2, time2 = my_keyboard.get_key()

Or pass the response options to keyboard.__init__:

# Get two key A or B presses with a 5000 ms timeout
my_keyboard = keyboard(keylist=[u'a', u'b'], timeout=5000)
key1, time1 = my_keyboard.get_key()
key2, time2 = my_keyboard.get_key()

function keyboard.__init__(experiment, **resp_args)

Constructor to create a new keyboard object. You do not generally call this constructor directly, but use the keyboard() function, which is described here: /python/common/.

Example:

my_keyboard = keyboard(keylist=['z', 'm'], timeout=2000)

Arguments:

  • experiment -- The experiment object.
    • Type: experiment

Keyword dict:

  • **resp_args: Optional [response keywords] (timeout and `

function keyboard.flush()

Clears all pending keyboard input, not limited to the keyboard.

Returns:

True if a key had been pressed (i.e., if there was something to flush) and False otherwise.

  • Type: bool

function keyboard.get_key(**resp_args)

Collects a single key press.

Example:

my_keyboard = keyboard()
response, timestamp = my_keyboard.get_key(timeout=5000)
if response is None:
        print(u'A timeout occurred!')

Keyword dict:

  • **resp_args: Optional [response keywords] (timeout and keylist) that will be used for this call to keyboard.get_key this does not affect subsequent operations.

Returns:

A (key, timestamp) tuple. key is None if a timeout occurs.

  • Type: tuple

function keyboard.get_mods()

Returns a list of keyboard moderators (e.g., shift, alt, etc.) that are currently pressed.

Example:

my_keyboard = keyboard()
moderators = my_keyboard.get_mods()
if u'shift' in moderators:
        print(u'The shift-key is down!')

Returns:

A list of keyboard moderators. An empty list is returned if no moderators are pressed.

  • Type: list

function keyboard.show_virtual_keyboard(visible=True)

Shows or hides a virtual keyboard if this is supported by the back-end. This function is only necessary if you want the virtual keyboard to remain visible while collecting multicharacter responses. Otherwise, keyboard.get_key will implicitly shown and hide the keyboard for a single-character response.

This function does nothing for back-ends that do not support virtual keyboards.

Example:

my_keyboard = keyboard()
my_keyboard.show_virtual_keyboard(True)
response1, timestamp2 = my_keyboard.get_key()
response2, timestamp2 = my_keyboard.get_key()
my_keyboard.show_virtual_keyboard(False)

Keywords:

  • visible -- True if the keyboard should be shown, False otherwise.
    • Type: bool
    • Default: True
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