Changing the value of an inserted point.
Wed, 10/03/2018 - 02:15 pm
This section is looking through lines of data looking for missing lines using the timestamp(Tmstamp). When a gap in time is found one point is inserted (and made a zero). The value of the tmstamp[i] is then set to one minute less than the next larger time value. This section works. Then i enter the for loop to add points to the other waves except the tmstamp wave. This works as well. Now I want to change the zeros that have been added to the other waves to -999 so that they can be identified when plotting. I cannot get this to work. I'm certain it's syntax. I've looked in the help files and they are not clear enough for me. I'm sure it has something to do with the wave reference but... Thanks for the help in advance.
ssmith911
INSERTPOINTS i,1,tmstamp //If True insert point in front of index i, 1 point, in wave "tmpstamp"
tmstamp[i] = (tmstamp[i+1] - 60) //Changes the inserted zero to 60 seconds less than the following point.
//This FOR loop uses the missing time index from tmstamp to insert missing points into the data waves
//Then it set those points -999.
FOR(a=0; a<(itemsinlist(listowaves)); a+=1)
WavNam = stringfromlist(a, listowaves)
IF(CmpStr(wavnam, "TmStamp") != 0) //When comparing strings one must use the CMPSTR function
INSERTPOINTS i, 1, $Wavnam
// wavnam[i] = (-999)
ENDIF
ENDFOR
// wavnam[i] = (-999)
wave w=$wavnam
w[i]=-999
October 3, 2018 at 02:31 pm - Permalink
Thanks Tony. Could you explain whats going on here and why it has to be done in this manner? Thanks again.
S
October 4, 2018 at 05:25 am - Permalink
In reply to Thanks Tony. Could you… by ssmith911
Your code would have attempted to assign a numeric value (999) to a "WavNam", which is a string and not a wave (nor a numeric variable). You need to locally declare the wave whose name is stored in WavNam. That's what Tony's line, "wave w=$wavnam", does. It declares the wave whose name is stored in WavNam locally as wave w. Then you're able to make the assignment.
The "$" dereferences WavNam and returns the wave reference to the wave whose name is stored in WavNam. run displayhelptopic "wave references" for more info.
Your other line is similar
INSERTPOINTS i, 1, $Wavnamit would not have worked without the $ because insertpoints works on waves and not on strings.
Some functions like insertpoints do not require you to locally declare the wave, while setting point values in waves does.
October 4, 2018 at 10:12 am - Permalink
In reply to Thanks Tony. Could you… by ssmith911
Sorry, I should have added a couple of lines of explanation.
This may help:
DisplayHelpTopic "Accessing Waves In Functions"
DisplayHelpTopic "Converting a String into a Reference Using $"
October 4, 2018 at 10:16 am - Permalink
Another good reference is DisplayHelpTopic "Accessing Global Variables And Waves"
That explains the compile-time and run-time actions of a WAVE, NVAR or SVAR statement.
October 4, 2018 at 10:30 am - Permalink
thank you all very much. I appreciate the help.
ssmith911
October 5, 2018 at 06:05 am - Permalink
In reply to thank you all very much. I… by ssmith911
If you're using Igor 8 you can set the value as you insert the point:
//This FOR loop uses the missing time index from tmstamp to insert missing points into the data waves
FOR(a=0; a<(itemsinlist(listowaves)); a+=1)
wave w = $(stringfromlist(a, listowaves)) // w references ath wave in listowaves
INSERTPOINTS /V=-999 i, 1, w
ENDFOR
tmstamp[i] = (tmstamp[i+1] - 60) // Changes the inserted -999 to 60 seconds less than the following point.
October 5, 2018 at 06:49 am - Permalink