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.


# Retrieve vector that counts number of observations mt_count(mt_example$trajectories)
#> 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