# Re: [ferret_users] Trying to understand logic behind stick plot

Hi,
Have you been able to read your data into Ferret? UTC simply means Coordinated Universal Time, but what is the data unit?  Seconds, maybe?  and since what time origin? Your data source should tell you more than just "UTC".

Ferret will be able to convert those data to time steps once one knows that.  You would read in the three variables, define a time axis using the first one, and RESHAPE your u and v components to that time axis. Fill in the right things in the DEFINE AXIS command, and you should be set.
yes? file/var="tsec, zero, u, v" my_data.dat
yes? define axis/t/units=seconds/t0="???" timeax = tsec
yes? let ucomp = reshape(u,t[gt=timeax])
yes? let vcomp = reshape(v,t[gt=timeax])
It would be a good idea  to add /UNITS=  on the  LET commands to give the velocity components their correct units.  Then you should be able to try the stick_vectors script to make a plot.

Ansley

On 6/30/2014 5:42 AM, 'Don DNA' via _OAR PMEL Ferret Users wrote:
I read answer from ferret userlist regarding stick plot from here, and I don't have much knowledge about ferret, even to read source code

http://www.pmel.noaa.gov/maillists/tmap/ferret_users/fu_2011/msg00591.html

 View on www.pmel.noaa.gov Preview by Ya

I have "UTC date, u - component, v-component " I am interested to calculate time shift, can someone please help me to calculate time shift for line segments,

My data looks something like this

UTC data, Zero, U-comp, V-component
379987200000,0, -3.969,0.596
382665600000,0, -4.578,-1.001
385084800000,0,1.593,0.484
387763200000,0, -1.622,1.58

Can someone please explain me, time shift for above input, I actually did not understand this "from (c*t, 0) to (c*t+u(t), v(t))", if I just add utc date to U(t) - component I will get very close value and I will not get slope, please help me..

- Dona