Modifying creation date of a wave

Share icon

I would like to be able to modify the creation date of a wave. (I know this is heresy!)

My waves are taken from an oscilloscope, so I'd like to put the trigger time stamp into the creation time. This could then be retrieved by creationdate(wave), and remain a fixed value despite other operations on the wave. The trigger time may differ from the wave creation time if the trace is not downloaded from the scope immediately.
You could avoid being burned as a heretic by using 'note':
 Note <waveName>,"CREATIONDATE="+<your date here>+";"
and extracting with stringByKey("CREATIONDATE",note(<waveName>),"=",";") at any later time. The KEY=VALUE; approach allows you to put any number of data points in any order, as a bonus.
Regards,
Patrick.

May 18, 2009 at 09:36 pm - Permalink

If you don't mind being heretical...
I have written a function which lets you set the creation date of a igor binary wave. It requires that the wave is saved to disk as .ibw file. You can't process a wave which is part of a Igor experiment, but temporarily write a wave do disk, change the creation date, load the wave back in and then delete the file shouldn't be so difficult.

Here comes the code:
#pragma rtGlobals=1     // Use modern global access method.
 
function modifyCreationDate(year,month,day,hour,minute,second)
    variable year,month,day,hour,minute,second
 
    string oldDF=getdatafolder(1)
    string newDF=uniquename("newDF",11,0)
    newdatafolder/s $newDF
    variable creationDateMOD=date2secs(year,month,day)+hour*3600+minute*60+second
    variable refnum,version,creationDatePos,headerlenAsWords,checksumPos
    open/t=".ibw"/m="choose ibw file"/z=2/a refnum
//  print V_flag
    if(V_flag!=0)
        setdatafolder $oldDF
        killdatafolder $newDF
        return V_flag
    endif
    fstatus refnum
    
    // get igor binary version:
    fsetpos refnum,0
    fbinread/f=2 refnum,version
    switch(version)
        case 2:
            creationDatePos=112
            checksumPos=14
            headerlenAsWords=142/2
            break
        case 5:
            creationDatePos=68
            checksumPos=2
            headerlenAsWords=384/2
            break
        default:
            print "Couldn't determine Igor binary version!"
            fsetpos refnum,V_logEOF
            close refnum
            setdatafolder $oldDF
            killdatafolder $newDF
            return version
    endswitch
//  print version
    
    // write new creation date:
    fsetpos refnum,creationDatePos
    fbinwrite/f=3/u refnum,creationDateMOD
    
    // calculate checksum:
    make/o/n=(headerlenAsWords)/w W_header
    fsetpos refnum,0
    fbinread refnum,W_header
    W_header[checksumPos/2]=0
    make/o/n=1/w W_checksum= -sum(W_header)
    
    // write ckecksum:
    fsetpos refnum,checksumPos
    fbinwrite refnum,W_checksum
    
    // clean up:
    fsetpos refnum,V_logEOF
    close refnum
    setdatafolder $oldDF
    killdatafolder $newDF
    
    return creationDateMOD
end

May 19, 2009 at 04:50 am - Permalink