LI-COR LI-6400, Manual

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GraphIt
Selecting Observations
Using the LI-6400 12-11
Using Every n
th
Observation
If your data represents a long time series with many observations, it will be
advantageous to subsample the data when plotting it. For example, instead of
plotting each observation, you may wish to plot every 10th observation.
To define a subsample interval, press Ò Pick Data Set Ó ( f1 level 2), then S . You
will be prompted to enter a value n , where n =1 means use every line, n =2
means use every other line, etc.
Logic Based Inclusion
Sometimes you may wish to include or exclude observations based on the val-
ues of the data for that observation. For example, suppose you have a file of
survey data for sunlit and shaded leaves, and you wish to plot photosynthesis
vs. conductance for sunlit leaves only. You could do this with GraphItÕs logic
option by specifying only observations with PAR greater than some threshold
value, such as 1000 µmol m
-2
s
-1
.
Inclusion logic is defined by pressing Ò Edit Config Ó ( f4 level 1) then L from
GraphItÕs main screen (short cut: just press
L
from the main screen). The logic
screen (Figure 12-10) appears, and you can type in or edit the logical state-
ment to be used.
Figure 12-9. Prompting for the Label Line. Put the highlighted bar on
the label line, and press enter. This will happen automatically when
GraphIt first runs, if the label line does not begin with ÒObs, as is the
case in this example. When selecting the data lines, the prompts will be
ÒSelect the FIRST DATA LINEÓ and ÒSelect the LAST DATA LINEÓ
Select the LABEL LINE
"Time","Photo","Cond","Ci","Trmmol","Ar
+ Print
¨
Find
¨
Refind
¨
CANCEL
¨
SELECT
"LightSource=","Sun+Sky",1,0.19
"LogFormat=","/User/Configs/LogFormats/
"1: grass"
20.2,15.4,0.216,238,3.49,1.62,3.5,1,3.49
104.2,11.3,0.202,180,3.33,1.65,3.5,1,3.4