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  • Description
  • Normalizes individual .p files from several paired groups (conditions) of EP files (.p). The output are normalised .norm.p files.

  • Usage
  • epnorm myparameterfile.par mycondfile.cond

    with :

    • myparameterfile.par : conversion parameter file (with extension).
    • mycondfile.cond : ascii file including the list of .p to process (see below).

  • Fields of parameter file and example
  • epnorm_channel_flag 1 1 0 0 1 List of the channels to normalize: 1/0 for selected/unselected channels.
    epnorm_time_hw 50 Half-window size (in ms) of smoothing window. If the value is set to 0, no smoothing is applied, and all samples are computed.
    epnorm_time_step 50 Time step (in ms) of smoothing window.
    epnorm_normalization 1 Normalization type. Possible values are :
    0: no normalization
    1: for each subject, each sample is divided by the norm of the vector in channel  condition space
    2: for each subject and each condition, each sample is divided by the norm of the vector in channel space
    3: for each condition and sample, each sample is divided by the norm of the mean vector (across subjects) in channel space
    4, 5, 6: same as 1, 2, 3 except that the maximum norm in the analysis time-window is taken
    epnorm_lat_beg_ms 100 Beginning latency for normalization (in ms).
    epnorm_lat_end_ms 300 Ending latency for normalization (in ms).

    The condition file is a text file formatted as follow:

    Parameter (example) Comment
    1 2 4 Number of factors (must be 1).
    Number of conditions for this factor (must be 2).
    Number of .p files for each condition.
    fact1 cond1 suj1 Myfile_cond1_suj1.p
    fact1 cond1 suj2 Myfile_cond1_suj2.p
    fact1 cond1 suj3 Myfile_cond1_suj3.p
    fact1 cond1 suj4 Myfile_cond1_suj4.p
    fact1 cond2 suj1 Myfile_cond2_suj1.p
    fact1 cond2 suj2 Myfile_cond2_suj2.p
    fact1 cond2 suj3 Myfile_cond2_suj3.p
    fact1 cond2 suj4 Myfile_cond2_suj4.p
    List of .p files preceded by the following labels:
    name of the factor
    name of the condition
    name of the subject
    name of the .p file
    Each file in condition 1 has its paired file in condition 2.
    For one-sided tests, the condition with the predicted most positive mean must be placed first.

  • Examples

  • Comments
    1. All EP files should be compatible (in terms of number of channels and samples, number of pre-stimulus samples, sampling frequency) to the first EP file (file 1 in condition 1).
    2. Note that this program may use epranddiff parameters (eprand_channel_flag, eprand_time_hw, eprand_time_step, eprand_normalization, eprand_lat_beg_ms, eprand_lat_end_ms) instead of its own parameters.

  • Current version
  • 1.07 14-08-2012

  • History
    • 1.00 21-03-2006 (PEA) : 1st version.
    • 1.01 23-03-2006 (JB) : adds maximum norm, smoothing window.
    • 1.02 29-03-2006 (JB) : normalizes smoothed values. Adds parameter file. Reads epranddif parameters.
    • 1.03 23-03-2006 (JB) : fixes error with subsampling.
    • 1.04 22-05-2006 (JB) : fixes error with subsampling (time 0), improves test of compatibility of files.
    • 1.05 29-09-2010 (PEA) : updates to use cmake and free release of Elan.
    • 1.06 26-01-2011 (PEA) : removes static allocation for reading and writing EP files.
    • 1.07 14-08-2012 (PEA) : fixes error when reading files 2nd time (1st for compatibility check, 2nd for data). File name was freed after 1st read.

  • Files
  • $ELANPATH/bin/epnorm

  • See also
  • epranddiff