Backup diff of QuickLookPscript vs current(No. 14)

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* A Quick Look at Praat Scripting [#ncd89e32]
- This page is intended as a brief but somewhat "unorthodox" introduction to Praat scripting.
-- The primary target readers are ones who have some (partial) knowledge about programming/script language (e.g., C, perl, awk, python, VBA), and thus know, say, what ''array/if (conditional)/for (iteration, loop)'' mean. If you new to programming, see other sources((Highly recommended: Ingmar Steiner (2006-2007) '''Automatic Speech Data Processing with Praat'''. Lecture Notes. (PDF file is available at: http://www.coli.uni-saarland.de/~steiner/praat/lecturenotes.pdf .) )).
-- The contents are fragmentary. For unknown commands, consult ''Help'' in Praat first. It provides you valuable information.

''Table of Contents''
#contents

** Hello world [#xbb42d70]
+ Choose ''New Praat script'' from the ''Praat menu'' to open the ScriptEditor window.
+ Type:
 echo Hello world
+ Choose ''Run'' from the ''Run menu'' (or type C-r) to execute.

- '''Cf.''' [[Scripting 3.1. Hello world>http://www.fon.hum.uva.nl/praat/manual/Scripting_3_1__Hello_world.html]] (official site)

** Language Specification Worth Mentioning [#b3a53f90]

*** General [#k6026e40]

//- No declaration is required to use a variable.

- Output to the Info Window: ''echo'', ''printline'', and ''print''
--The three scripts below work in the same way (''clearinfo'' clears the Info window):
---
 echo Hello world
---
 clearinfo
 printline Hello world
---
 clearinfo
 print Hello world'newline$'
-- The two scripts below, however, do not work in the same way.
--- 
 echo This is the first sentence.
 echo This is the second sentence.
---
 clearinfo
 printline This is the first sentence.
 printline This is the second sentence.
- Comments
-- "''#''" and "'';''" are comment characters. Praat ignores the comment characters and after them, to the end of the line.
-- Use ";" instead of "#", if you want to write a comment after a statement in the same line.
 n = 0 
 if n = 0 ;conditional
     clearinfo
     printline Hello world
 endif
 # An error occurs if ";" is replaced with "#".
--- Some commands, however, cannot be followed by a comment in the same line. For example,
 n = 0 
 if n = 0 ;conditional
     clearinfo
     printline Hello world  ; This sentence is also displayed on the Info window.
 endif
// # Hello world script in Praat
// echo Hello world   ; This sentence is also displayed on the Info window.

- Variable Types
-- numerics and strings
--- Variables (either numeric or string) must begin with lower cases.
--- String variables must end with ''$''.
 str$ = "foo"
 num = 3
 ### statements below causes an error. ###
 #Str$ = "foo"  ; it begins with Upper case.
 #Num = 3
 #str = "foo"   ; it lacks $, though it has a string.
-- Arrays are also available.
--- The indices are enclosed with ''"["'' and ''"]"''
--- Like scalars, arrays must begin with lower cases.
--- Similarly, arrays which store strings must have ''$'' before ''"["''
 str$[1] = "foo"
 str$[2] = "bar"
 str$[3] = "hoge"
 str$[4] = "piyo"
 num[1] = 3
 num[2] = 34
 num[3] = 22
 num[4] = 98
 ### statements below causes an error. ###
 #str[1] = "foo"   ; it lacks $, though it has a string.
 #Num[4] = 98      ; it begins with Upper case.
-- Unfortunately, hashes (or associative arrays) are not available.

- Variable Substitution
-- Variables are substituted when put between single quotes.
 fruit$ = "apple(s)"
 count = 3
 echo I bought 'count' 'fruit$'.
--- ''NOTE1:'' No double quotations are required to literals in ''print'' (and ''printline'' and ''echo''). Compare
 fruit$ = "apple(s)"
 count = 3
 echo "I bought" 'count' 'fruit$' "."
--- ''NOTE2:'' If the index in an array is also a variable, a dummy variable is required.
 str$[1]= "apple"
 str$[2]= "orange"
 str$[3]= "melon"
 
 clearinfo
 for i from 1 to 3
     hop$ = str$[i]   ;; a dummy variable
     printline 'i''tab$''hop$'
 endfor

- Operators
-- Comparison Operators
--- The "equal" operator is "="((In fact, "==" can also be used as an equal operator.)), identical with the assignment operator.
 num = 3
 str$ = "hoge"
 
 clearinfo
 if num = 3
     printline 'num'
 endif
 
 if str$ = "hoge"
     printline 'str$'
 endif

-- Strings
--- Basically, operators used for numerics are also applicable to strings. 
--- Interestingly, not only string "addition" (i.e., concatenation), but also string "subtraction" (i.e., truncation) is possible, using "+" and "-".
 str1$ = "abc"
 str2$ = "def"
 str3$ = "c"
 
 str4$ = str1$ + str2$
 str5$ = str1$ - str3$
 
 clearinfo
 printline 'str4$'
 printline 'str5$'
--- result:
 abcdef
 ab
-- autoincrement/autodecrement operators (e.g., i++, i--) are not available.

- Conditional statements
-- ''if(-elsif)(-else)-endif''
--- ''NOTE:'' ''elsif'' (or ''elif''), rather than ''elseif'' and ''else if''.

- Loops
-- ''for i (from m) to n-endfor'', ''while-endwhile'', ''repeat-until'' 
--- ''from m'' in ''for'' can be omitted when m = 1.
--- It is not possible to decrement the loop counter in ''for''-loop. Use ''while-endwhile'', instead.
 n = 10
 clearinfo
 while n >= 1
     printline 'n'
     n = n-1
 endwhile
--- There seems to be no statement which escapes from the loop (''break'' in C, or ''last'' in perl). Instead, you can substitute the loop counter (or something) with a value which does not satisfy the loop condition, for example.
 clearinfo
 max = 10
 for i to max
     if i = 5
         i = max+1      ; escape from the loop
     else
         printline 'i'
     endif
 endfor

- ''goto'' is not available.
- ''goto'' is %%not%% available. &color(red){(modified July 17, 2012)};
 # the "goto" command in Praat scripts
 clearinfo
 for i to 10
     if i mod 2 = 0
         goto next
     endif
     printline 'i'
     label next
 endfor

- Subroutines: ''procedure-endproc''

- Regular expressions are available in some string functions:
-- ''index_regex(str$,regex$)''
-- ''rindex_regex(str$,regex$)''
-- ''replace_regex$(str$,regex$,substr$,n)''
--- ''NOTE:'' Functions which return strings (not numerics) require ''$''.
 str$ = "abcdefg"
 regex$ = "b[^e]*"
 clearinfo
 if index_regex(str$,regex$) <> 0
     printline match
 else
     printline not match
 endif

- Generally, index numbers start at 1 (not 0).
-- Check, for example, the value of the following string functions:
--- ''mid$(str$,index,len)''
 str$ = "abcdefg"
 len = length(str$)
 clearinfo
 for i from 1 to len
     hop$ = mid$(str$,i,1)
     printline 'i''tab$''hop$'
 endfor
--- ''index(str$,substr$)''
 str$ = "abcdefg"
 substr$ = "bcd"
 clearinfo
 n = index(str$,substr$)
 printline 'n'

- File IO
-- ''text$ <'' '''filename''' (read the contents of '''filename''')
 file$ = "d:\foo.txt"
 text$ < 'file$'
 clearinfo
 print 'text$'
-- ''text$ >'' '''filename''' (make a new file and write the contents of text$)
-- ''text$ >>'' '''filename''' (add the contents of text$ to '''filename''')
 file$ = "d:\bar.txt"
 text$ = "praat scripting is fun." + "'newline$'"
 text$ > 'file$'
 #text$ >> 'file$'
-- ''NOTE:'' Consider the use of ''Object'', rather than "''<''" or "''>''". Very often, Object manipulation is easier and more straightforward. For Object, see below.
//, especially when it contains multiple lines .

*** Particular to Praat (1): Object Manipulation [#e34387b5]
RIGHT:&color(red){Those who conquer object manipulation techniques conquer Praat scripting. (The present author)};

*** Particular to Praat (2): form-endform [#z692053a]
- ''form'' and ''endform''

//- ''system''
// # Windows
// system dir > hoge.txt && start notepad.exe hoge.txt
//
//- ''nocheck'' '''command'''
//-- equivalent to ''on error resume next'' in some scripts
//
//- ''exit'' ('''message''')  and ''pause'' ('''message''') 


** Functions of ScriptEditor [#m4b8a142]
- History
- Run a script

** Other ways to execute a script [#c753a9f4]

- praatcon.exe (in Windows)
- sendpraat.exe
-- scripts can be executed by using sendpraat.exe or praatcon.exe.
-- You may use option -a in praatcon.exe if you handle Unicode. (cf. [[Re: [praat-users] Bug in latest praatcon version (by Paul Boersma)>http://uk.groups.yahoo.com/group/praat-users/message/4950]]