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Common functions

The following functions are available in inline_script items:

Canvas(auto_prepare=True, **style_args)

A factory function that creates a new Canvas object. For a description of possible keywords, see:

Returns

  • A Canvas object.

Example

my_canvas = Canvas(color=u'red', penwidth=2)
my_canvas.line(-10, -10, 10, 10)
my_canvas.line(-10, 10, 10, -10)
my_canvas.show()

Experiment(osexp_path=None, log_path='defaultlog.csv', fullscreen=False, subject_nr=0, **kwargs)

A factory function that creates a new Experiment object. This is only useful when implementing an experiment entirely through a Python script, rather than through the user interface.

Parameters

  • osexp_path: If a path to an .osexp file is specified, this file is opened and can be run directly by calling Experiment.run(). If no experiment file is specified, an empty experiment is initialized.
  • log_path:
  • fullscreen:
  • subject_nr:
  • kwargs: Optional keyword arguments that are interpreted as experimental variables. The main use of this is to specify the backend through the canvas_backend keyword.

Returns

  • An (exp, win, clock, log) tuple corresponding to the Experiment, window handle (backend-specific), Clock, and Log objects.

Example

To implement an experiment fully programmatically:

from libopensesame.python_workspace_api import (
    Experiment, Canvas, Text, Keyboard)
exp, win, clock, log = Experiment(canvas_backend='legacy')
c = Canvas()
c += Text('Press any key')
c.show()
kb = Keyboard()
kb.get_key()
exp.end()

To load an experiment file and run it:

from libopensesame.python_workspace_api import Experiment
exp, win, clock, log = Experiment(osexp_path='my_experiment.osexp',
                                  subject_nr=2)
exp.run()

Form(*args, **kwargs)

A factory function that creates a new Form object. For a description of possible keywords, see:

Returns

  • A Form object.

Example

form = Form()
label = Label(text='label')
button = Button(text='Ok')
form.set_widget(label, (0,0))
form.set_widget(button, (0,1))
form._exec()

Keyboard(**resp_args)

A factory function that creates a new Keyboard object. For a description of possible keywords, see:

Returns

  • A Keyboard object.

Example

my_keyboard = Keyboard(keylist=[u'a', u'b'], timeout=5000)
key, time = my_keyboard.get_key()

Mouse(**resp_args)

A factory function that creates a new Mouse object. For a description of possible keywords, see:

Returns

  • A mouse object.

Example

my_mouse = Mouse(keylist=[1,3], timeout=5000)
button, time = my_mouse.get_button()

Sampler(src, **playback_args)

A factory function that creates a new Sampler object. For a description of possible keywords, see:

Returns

  • A sampler object.

Example

src = pool['bark.ogg']
my_sampler = Sampler(src, volume=.5, pan='left')
my_sampler.play()

Synth(osc='sine', freq=440, length=100, attack=0, decay=5, **playback_args)

A factory function that synthesizes a sound and returns it as a Sampler object.

Parameters

  • osc: Oscillator, can be "sine", "saw", "square" or "white_noise".
  • freq: Frequency, either an integer value (value in hertz) or a string ("A1", "eb2", etc.).
  • length: The length of the sound in milliseconds.
  • attack: The attack (fade-in) time in milliseconds.
  • decay: The decay (fade-out) time in milliseconds.
  • **playback_args: Optional playback keywords, such as volume and pan, as described under /python/sampler/.

Returns

  • A sampler object.

Example

my_sampler = Synth(freq='b2', length=500)

copy_sketchpad(name)

Returns a copy of a sketchpad's canvas.

Parameters

  • name: The name of the sketchpad.

Returns

  • A copy of the sketchpad's canvas.

Example

my_canvas = copy_sketchpad('my_sketchpad')
my_canvas.show()

pause()

Pauses the experiment.

register_cleanup_function(fnc)

Registers a clean-up function, which is executed when the experiment ends. Clean-up functions are executed at the very end, after the display, sound device, and log file have been closed. Clean-up functions are also executed when the experiment crashes.

Example

def my_cleanup_function():
        print(u'The experiment is finished!')
register_cleanup_function(my_cleanup_function)

reset_feedback()

Resets all feedback variables to their initial state.

Example

reset_feedback()

set_subject_nr(nr)

Sets the subject number and parity (even/ odd). This function is called automatically when an experiment is started, so you only need to call it yourself if you overwrite the subject number that was specified when the experiment was launched.

Parameters

  • nr: The subject nr.

Example

set_subject_nr(1)
print('Subject nr = %d' % var.subject_nr)
print('Subject parity = %s' % var.subject_parity)

sometimes(p=0.5)

Returns True with a certain probability. (For more advanced randomization, use the Python random module.)

Parameters

  • p: The probability of returning True.

Returns

  • True or False

Example

if sometimes():
        print('Sometimes you win')
else:
        print('Sometimes you loose')

xy_circle(n, rho, phi0=0, pole=(0, 0))

Generates a list of points (x,y coordinates) in a circle. This can be used to draw stimuli in a circular arrangement.

Parameters

  • n: The number of x,y coordinates to generate.
  • rho: The radial coordinate, also distance or eccentricity, of the first point.
  • phi0: The angular coordinate for the first coordinate. This is a counterclockwise rotation in degrees (i.e. not radians), where 0 is straight right.
  • pole: The reference point.

Returns

  • A list of (x,y) coordinate tuples.

Example

# Draw 8 rectangles around a central fixation dot
c = Canvas()
c.fixdot()
for x, y in xy_circle(8, 100):
        c.rect(x-10, y-10, 20, 20)
c.show()

xy_distance(x1, y1, x2, y2)

Gives the distance between two points.

Parameters

  • x1: The x coordinate of the first point.
  • y1: The y coordinate of the first point.
  • x2: The x coordinate of the second point.
  • y2: The y coordinate of the second point.

Returns

  • The distance between the two points.

xy_from_polar(rho, phi, pole=(0, 0))

Converts polar coordinates (distance, angle) to Cartesian coordinates (x, y).

Parameters

  • rho: The radial coordinate, also distance or eccentricity.
  • phi: The angular coordinate. This reflects a clockwise rotation in degrees (i.e. not radians), where 0 is straight right.
  • pole: The reference point.

Returns

  • An (x, y) coordinate tuple.

Example

# Draw a cross
x1, y1 = xy_from_polar(100, 45)
x2, y2 = xy_from_polar(100, -45)
c = Canvas()
c.line(x1, y1, -x1, -y1)
c.line(x2, y2, -x2, -y2)
c.show()

xy_grid(n, spacing, pole=(0, 0))

Generates a list of points (x,y coordinates) in a grid. This can be used to draw stimuli in a grid arrangement.

Parameters

  • n: An int that indicates the number of columns and rows, so that n=2 indicates a 2x2 grid, or a (n_col, n_row) tuple, so that n=(2,3) indicates a 2x3 grid.
  • spacing: A numeric value that indicates the spacing between cells, or a (col_spacing, row_spacing) tuple.
  • pole: The reference point.

Returns

  • A list of (x,y) coordinate tuples.

Example

# Draw a 4x4 grid of rectangles
c = Canvas()
c.fixdot()
for x, y in xy_grid(4, 100):
        c.rect(x-10, y-10, 20, 20)
c.show()

xy_random(n, width, height, min_dist=0, pole=(0, 0))

Generates a list of random points (x,y coordinates) with a minimum spacing between each pair of points. This function will raise an Exception when the coordinate list cannot be generated, typically because there are too many points, the min_dist is set too high, or the width or height are set too low.

Parameters

  • n: The number of points to generate.
  • width: The width of the field with random points.
  • height: The height of the field with random points.
  • min_dist: The minimum distance between each point.
  • pole: The reference point.

Returns

  • A list of (x,y) coordinate tuples.

Example

# Draw a 50 rectangles in a random grid
c = Canvas()
c.fixdot()
for x, y in xy_random(50, 500, 500, min_dist=40):
        c.rect(x-10, y-10, 20, 20)
c.show()

xy_to_polar(x, y, pole=(0, 0))

Converts Cartesian coordinates (x, y) to polar coordinates (distance, angle).

Parameters

  • x: The X coordinate.
  • y: The Y coordinate.
  • pole: The reference point.

Returns

  • An (rho, phi) coordinate tuple. Here, rho is the radial coordinate, also distance or eccentricity. phi is the angular coordinate in degrees (i.e. not radians), and reflects a counterclockwise rotation, where 0 is straight right.

Example

rho, phi = xy_to_polar(100, 100)
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