Scripting with Praat. Day 8: More Goodies and the Way Forward

Transcription

1 Scripting with Praat Day 8: More Goodies and the Way Forward 1

2 Today Note on arrays Regular expressions Editor scripts and extending Praat functionality Simple experiments with ExperimentMFC User interaction with the Demo window Where to go from here? 2

3 A note about arrays Arrays can also take strings as indices instead of numbers In this case they may be called "dictionaries" instead of "arrays" For example: age["john"] = 36 age["sarah"] = 42 writeinfoline: "Sarah is ", age["sarah"]-age["john"],..." years older than John." 3

4 Regular Expressions "regex" (manual) Regular expressions are a powerful tool generally used for searching for strings / series of characters within some text A regular expression serves as a formal description of a pattern that describes the set of strings to be searched for Characters that are used in the regex syntax are given special meanings Example: Suppose you wanted to find instances of only the following two words, either capitalized or not, excluding other related forms MATCH: phonetic(s) phonemic EXCLUDE: phone(s) phonetician(s) phoneme(s) prefixes (e.g., socio-, morpho-)

5 Regular Expressions example phonetic(s) phonemic EXCLUDE: phone(s) phonetician(s) phoneme(s) prefixes (e.g., socio-, morpho-) "^" matches the beginning of a line, "\s" matches whitespace Parentheses group characters together, " " means OR. "(P p)" = 1 occurrence of "P" OR "p"; (^ \s) = beginning of line or of word "hone" will match those four characters in sequence The square brackets define a character class that will match a single character from among the listed choices "ic" will match those characters in sequence (^ \s)(p p)hone[mt]ics? "?" matches zero or one of the preceding character (here, "s")

6 Regular Expressions in string functions (manual) Three string functions in Praat use regular expressions to find or replace strings: index_regex, rindex_regex, and replace_regex$ index_regex( string$, regex$ ) determines character position where the string string$ first matches the regex regex$. If there is no match, the result is 0. Example: match = index_regex ( "internationalization", "a.*n" ) In this case, the variable match contains the number 7. The regex "a.*n" matches any sequence beginning with "a" and ending with "n" with any number of characters other than "n" in between "." = match any single character "*" = quantifier, match zero or more of the preceding character

7 Regular Expressions in string functions (manual) rindex_regex (string$, regex$) does the same thing from the right hand edge of the string, i.e., finds the character position where the text in string$ last matches the pattern in regex$. Example: where = rindex_regex ("internationalization", "a.*n") The variable where contains the number 16. replace_regex$ (string$, regex$, replacement$, n) replaces up to n occurrences of strings matched by regex$ in string$ with replacement$ if n=0, all occurrences are replaced returns the original string if there are no matches

8 Exercise: regex Count the number of occurrences of the "s" character, NOT including the sequence "sh", in this string: "she sells seashells by the seashore" Your output should be the total count followed by a list of which positions in the string contain "s" but not "sh"

9 Scripting the editor(s) (manual) Praat has 13 editors, i.e., the windows that pop up when you select an object and press "View & Edit" Somewhat oddly, it also has a separate ScriptEditor for each Editor, in addition to the Objects window ScriptEditor (so a total of 14 ScriptEditors). Sometimes, you might want to write a script that will control one of these Editors, using the editor-specific ScriptEditor Within each Editor's File menu are "New Praat script" and "Open Praat script " commands A script originally written within a particular Editor will not work if opened from the Praat menu/objects window, and vice versa!! (this is something to watch out for when using other people's scripts)

10 Scripting the editor(s) (manual) The main ScriptEditor (the one we've been using) can add commands to the Objects window or the Picture window. Go to Praat --> New Praat Script --> File and see the selections "Add to fixed menu..." and "Add to dynamic menu..." The editor-specific ScriptEditors can add scripts to the drop-down menus in that editor. (File menu within the editor-specific ScriptEditor) Normally, it makes sense to write an editor-specific script when the script will become a new button or menu command within that editor Example: draw_spectrum_from_selection.praat (must be opened from within an Editor)

11 Exercise: Extending Praat Open JFK_Moon_Rice.wav from day8code/sounds/ Select the sound and open the SoundEditor window. In the SoundEditor, choose File --> Open editor script... and open draw_sprectrum_from_selection.praat In the ScriptEditor, use "Add to menu..." to add this command to the Spectrum menu. Call it something like "Draw spectrum from selection" Now close and reopen the SoundEditor window to use the menu command

12 Exercise: TextGrid Editor Create a TextGrid for the JFK sound object Open the Sound and TextGrid objects together. Look in the Spectrum menu. Why isn't the "Draw spectrum from selection" script in the Spectrum menu? Can you add it?

13 Exercise: Removing commands/buttons What if you need to update a script that you've added to a menu? Or you just don't need it anymore and don't want it cluttering up your menus? ButtonEditor!! Praat -> Preferences -> Buttons In the "Editors" tab, click "ADDED" to change it to "REMOVED" Quit and restart Praat

14 ExperimentMFC (manual) Another type of Object in Praat used for running simple identification and discrimination "Multiple Forced Choice" perception experiments Good documentation in the manual you essentially just copy the skeleton for the type of experiment you want to run from the manual and alter the settings, options, and details about filenames to fit your particular needs Let's look at one example: ExperimentMFC_example.txt To open: Read from file "Run" to run the experiment "Extract results" to get results after running "Collect to Table" to view in table format "Save to tab-separated file: <xxxx>.txt" to save for analysis in other software 14

15 Manipulating Sounds (manual) If you are running an experiment, in Praat or some other software, you may need to do some sound manipulation and resynthesis to create stimuli Manipulation Objects allow you to alter the pitch and duration of a Sound object Manipulation of intensity and formants is also possible in Praat But we'll just look at an example of altering pitch samplemanipulation.praat 15

16 User interaction: the Demo window (manual) Demo window only available through scripts Allows drawing (same commands as Paint window, but preceded by "demo") Takes user input through mouse clicks and key presses Let's look at a demo demo demodemo.praat 16

17 Table objects to extract subsets for presentation Participant IDs and demographic/linguistic/other data by which you wish to categorize them can be stored in a Table object Use family of commands "Extract rows where " to extract subsets of the Table (by rows) based on values in relevant columns Can use indexing and index_regex functions in the extraction command to check whether a value occurs within some lookup list Example: tableextraction.praat 17

18 So what's the way forward? Write a lot of Praat scripts. Review the examples and try to re-write a lot of the scripts we've done in class yourself. Think about ways you might be able to improve them (more efficient? more robust?) as you do this. Review the code in scripts you already use (or new ones you find); make sure you understand everything they do. Use the manual, ask friends, ask google, ask the praat-users list if you can't figure something out. If you're not sure exactly how a command works, don't be afraid to test it on a simple task where you know the expected outcome. You won't break anything!! (though you will have to Force Quit Praat if you get stuck in an infinite loop :) (Re-)Read the Intro and Scripting chapters of the Praat manual (and other useful links within those sections and in the class slides). It will go faster this time and you'll learn things you missed the first time through. Teach someone else how to script in Praat!