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Generating simulated activation maps

The module fff2.utils.simul_2d_multisubject_fmri_dataset contains a function to create simulated 2D activation maps: make_surrogate_array(). The function can position various activations and add noise, both as background noise and jitter in the activation positions and amplitude.

This function is useful to test methods.

Example

import numpy as np
import pylab as pl

from nipy.neurospin.utils.simul_2d_multisubject_fmri_dataset import \
     make_surrogate_array

pos = np.array([[10, 10],
                [14, 20],
                [23, 18]])
ampli = np.array([4, 5, 2])

# First generate some noiseless data
noiseless_data = make_surrogate_array(nbsubj=1, noise_level=0, spatial_jitter=0,
                                signal_jitter=0, pos=pos, ampli=ampli)

pl.figure(figsize=(10, 3))
pl.subplot(1, 4, 1)
pl.imshow(noiseless_data[0])
pl.title('Noise-less data')

# Second, generate some group data, with default noise parameters
group_data = make_surrogate_array(nbsubj=3, pos=pos, ampli=ampli)

pl.subplot(1, 4, 2)
pl.imshow(group_data[0])
pl.title('Subject 1')
pl.subplot(1, 4, 3)
pl.title('Subject 2')
pl.imshow(group_data[1])
pl.subplot(1, 4, 4)
pl.title('Subject 3')
pl.imshow(group_data[2])

[source code, hires.png, pdf]

../_images/surrogate_array.png

Function documentation