Count number of observations per trial for a specified dimension (or several) in the trajectory array. This is mostly a helper function used by other functions in this package.

mt_count(data, use = "trajectories", save_as = "measures", dimensions = "xpos")



a mousetrap data object created using one of the mt_import functions (see mt_example for details). Alternatively, a trajectory array can be provided directly (in this case use will be ignored).


a character string specifying which trajectory data should be used.


a character string specifying where the resulting trajectory data should be stored.


a character vector specifying the name of the dimension(s) that should be used for counting the number of observations. If several dimensions are specified, the number of complete observations are reported.


A mousetrap data object (see mt_example).

If a data.frame with label specified in save_as (by default "measures") already exists, the number of observations (called nobs) are added as additional column. If not, an additional data.frame

will be added.

If a trajectory array was provided directly as data, only a named character vector will be returned.


Pascal J. Kieslich


# Retrieve vector that counts number of observations
#> id01 id02 id03 id04 id05 id06 id07 id08 id09 id10 id11 id12 id13 id14 id15 id16 
#>  173  280  153  174  334  311  234  203  250  201  283  355  242  465  219  230 
#> id17 id18 id19 id20 id21 id22 id23 id24 id25 id26 id27 id28 id29 id30 id31 id32 
#>  158  355  398  121  145  167  117  102   80   89   85  125  110   81  105   72 
#> id33 id34 id35 id36 id37 id38 
#>  210  110  457  157  100  133