R Dynamic split/subset of dataframe by selected rownumbers- Parsing textgrid praat

Question 1

The length of the split vector should be equal to the number of rows in the data.frame.

Try the following:

txtgrid.sub <- txtgrid[-(1:grep("item", txtgrid$object)[1]), ]

grep("item", txtgrid.sub$object)[-1]

splits <- unlist(mapply(rep, seq_along(grep("item", txtgrid.sub$object)),
                        diff(c(grep("item", txtgrid.sub$object), 
                               nrow(txtgrid.sub) + 1))))

df.list <- split(txtgrid.sub, list(splits))

EDIT:

You could then simplify the data by doing something like this:

l <- lapply(df.list, function(x) {
  tmp <- as.data.frame(t(x[, 3, drop=FALSE]), stringsAsFactors=FALSE)
  names(tmp) <- make.unique(make.names(x[, 2]))
  tmp
})

library(plyr)
do.call(rbind.fill, l)


  item..1..        class     name xmin    xmax intervals..size
1      <NA> IntervalTier   phones    0 243.761            2505
2      <NA> IntervalTier syllable    0 243.761            2505
  intervals..1.. xmin.1             xmax.1 text intervals..2..
1           <NA>      0 0.4274939687384032    _           <NA>
2           <NA>      0 0.4274939687384032    _           <NA>
              xmin.2 xmax.2
1 0.4274939687384032  0.472
2               <NA>   <NA>

NB: I've used dummy data for the above.

Question 2

You seem to have found a good solution elsewhere, but I thought I might as well put this here for reference:

I recently finished a first working version of a JSON converter for Praat objects that could have been used for this. You can save the TextGrid as a JSON file using the script save_as_json.praat included in this plugin (again: I am the author of that plugin).

Copied from this other answer to a similar question, once you have the plugin installed you can use the script from the Save menu in Praat or run it like this from another script:

runScript: preferencesDirectory$ + "/plugin_jjatools/save_as_json.praat",
  ..."/output/path", "Pretty printed"

Once that is done, you can read it into R using rjson like this:

> library(rjson)
> tg <- fromJSON(file='/path/to/your_textgrid.json')
> str(tg)
List of 5
$ File type   : chr "json"
$ Object class: chr "TextGrid"
$ start       : num 0
$ end         : num 1.82
$ tiers       :List of 2
    ..$ :List of 5
    .. ..$ class    : chr "IntervalTier"
    .. ..$ name     : chr "keyword"
    .. ..$ start    : num 0
    .. ..$ end      : num 1.82
    .. ..$ intervals:List of 3
    .. .. ..$ :List of 3
    .. .. .. ..$ start: num 0
    .. .. .. ..$ end  : num 0.995
    .. .. .. ..$ label: chr ""
    .. .. ..$ :List of 3
    .. .. .. ..$ start: num 0.995
    .. .. .. ..$ end  : num 1.5
    .. .. .. ..$ label: chr "limite"
    .. .. ..$ :List of 3
    .. .. .. ..$ start: num 1.5
    .. .. .. ..$ end  : num 1.82
    .. .. .. ..$ label: chr ""
    ..$ :List of 5
    .. ..$ class    : chr "IntervalTier"
    .. ..$ name     : chr "segments"
    .. ..$ start    : num 0
    .. ..$ end      : num 1.82
    .. ..$ intervals:List of 8
    .. .. ..$ :List of 3
    .. .. .. ..$ start: num 0
    .. .. .. ..$ end  : num 0.995
    .. .. .. ..$ label: chr ""
    .. .. ..$ :List of 3
    .. .. .. ..$ start: num 0.995
    .. .. .. ..$ end  : num 1.07
    .. .. .. ..$ label: chr "l"
    .. .. ..$ :List of 3
    .. .. .. ..$ start: num 1.07
    .. .. .. ..$ end  : num 1.15
    .. .. .. ..$ label: chr "i"
    .. .. ..$ :List of 3
    .. .. .. ..$ start: num 1.15
    .. .. .. ..$ end  : num 1.23
    .. .. .. ..$ label: chr "m"
    .. .. ..$ :List of 3
    .. .. .. ..$ start: num 1.23
    .. .. .. ..$ end  : num 1.28
    .. .. .. ..$ label: chr "i"
    .. .. ..$ :List of 3
    .. .. .. ..$ start: num 1.28
    .. .. .. ..$ end  : num 1.37
    .. .. .. ..$ label: chr "t"
    .. .. ..$ :List of 3
    .. .. .. ..$ start: num 1.37
    .. .. .. ..$ end  : num 1.5
    .. .. .. ..$ label: chr "e"
    .. .. ..$ :List of 3
    .. .. .. ..$ start: num 1.5
    .. .. .. ..$ end  : num 1.82
    .. .. .. ..$ label: chr ""

Or using, for example, tg$tiers[[tier_number]]$intervals[[interval_number]].