t.test in a loop

Hi All,
I've been having a little trouble with creating a loop that will run a a
series of t.tests for inspection,
Below is the code i've tried, and some checks i've looked at.

I've used the get(paste()) idea as i was told previously that the use of the
eval should try and be avoided.

I've run a single syntax to check that my systax is correct and works
without any problems
t.test(channel.data.train$News~channel.data.train$power)
Can anyone offer any advice?
There's the additional problem that if your code worked it would do 16 t-tests but only report the last one.

Assuming you want them printed

for(v in names(channel.data.train)[1:16]) {
   print(v)
   print(t.test(channel.data.train[[v]]~channel.data.train$power)
}

or
for(v in names(channel.data.train)[1:16]){
   test <- eval(bquote(.(v)~power, data=channel.data.train)
   print(eval(test))
}

This sort of use of eval is fairly harmless.

        -thomas
Many thanks

Mike

str(channel.data.train$power)
num [1:9913] 0 0 0 0 0 0 0 0 0 0 ...
summary(channel.data.train$power)
  Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
0.0000  0.0000  0.0000  0.2368  0.0000  1.0000
names(channel.data.train)
[1] "News"              "Entertainment"     "Communicate"
[4] "Lifestyle"         "Games"             "Music"
[7] "Money"             "Celebrity"         "Shopping"
[10] "Sport"             "Film"              "Travel"
[13] "Cars"              "Property"          "Chat"
[16] "Bet.Play.Win"      "config"            "exposed"
[19] "site"              "referrer"          "started"
[22] "last_viewed"       "num_views"         "secs_since_viewed"
[25] "register"          "secs.na"           "power"
[28] "tt"
for(i in names(channel.data.train[,c(1:16)])){
+
t.test(get(paste("channel.data.train$",i,"~channel.data.train$power",sep="")))
+ }
Error in get(paste("channel.data.train$", i, "~channel.data.train$power",
:
 variable "channel.data.train$News~channel.data.train$power" was not found

--
Michael Pearmain
Senior Analytics Research Specialist

Google UK Ltd
Belgrave House
76 Buckingham Palace Road
London SW1W 9TQ
United Kingdom
t +44 (0) 2032191684
mpearmain at google.com

If you received this communication by mistake, please don't forward it to
anyone else (it may contain confidential or privileged information), please
erase all copies of it, including all attachments, and please let the sender
know it went to the wrong person. Thanks.

	[[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Thomas Lumley			Assoc. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle

t.test in a loop

Thread (3 messages)