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Thanks, Petr.&nbsp; Your insight has helped me out a lot. 

Billy 

Petr Savicky-2 [via R] wrote:
 On Mon, Mar 21, 2011 at 02:28:32PM -0700, armstrwa wrote:
  
&gt; Hi all,
  
&gt; 
&gt; Forgive me for this basic question. &nbsp;I've been doing some research
and
  
&gt; haven't been able to figure out how to best do this yet.
  
&gt; 
&gt; I have 75 variables defined as vector time series. &nbsp;I am trying to
create a
  
&gt; script to automate calculations on each of these variables, but I
wasn't
  
&gt; sure how to go about calling variables in a script.
  
&gt; 
&gt; I am hoping to write a loop that calls a list of variable names
and runs
  
&gt; several tests using each of the datasets I have entered.
  
&gt; 
&gt; For example, say I have a defined 5 variables: var1, var2,...var5.
&nbsp;How
  
&gt; could I create a script that would run, say, a MannKendall
correlation test
  
&gt; on each variable?
  
  
Hi.
  
  
A typical way, how to perform a loop over several variables, is
  
to keep the variables in a list. For example
  
  
&nbsp; lst &lt;- list(var1=2:5, var2=c(23, 56), var3=seq(0, 1, length=11))
  
&nbsp; lst
  
  
&nbsp; $var1
  
&nbsp; [1] 2 3 4 5
  
  
&nbsp; $var2
  
&nbsp; [1] 23 56
  
  
&nbsp; $var3
  
&nbsp; &nbsp;[1] 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
  
  
&nbsp; for (i in seq.int(along=lst)) {
  
&nbsp; &nbsp; &nbsp; print(mean(lst[[i]]))
  
&nbsp; }
  
  
&nbsp; [1] 3.5
  
&nbsp; [1] 39.5
  
&nbsp; [1] 0.5
  
  
It is also possible to loop over isolated variables. For example
  
  
&nbsp; var1 &lt;- 2:5
  
&nbsp; var2 &lt;- c(23, 56)
  
&nbsp; var3 &lt;- seq(0, 1, length=11)
  
&nbsp; for (varnam in c("var1", "var2", "var3")) {
  
&nbsp; &nbsp; &nbsp; x &lt;- get(varnam)
  
&nbsp; &nbsp; &nbsp; print(mean(x))
  
&nbsp; }
  
  
Hope this helps.
  
  
Petr Savicky.
  
  
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William Armstrong
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