[R] Simple:: usage of stem() and hist()?

[Alan Davis]

I must apologize in advance for asking a simple question.  I am sure that a clue will be sufficient to get this show on the road.  I am trying to graph tide prediction data in various ways.  I haven't been able to answer this question after pouring over TFM.  

I read the datafile
      theight <- read.table("tides",header=TRUE)

I do get a summary() or fivenum() 
      summary(theight)
      fivenum(theight)

But when I run
      stem(theight), I receive CONSISTENTLY the following message, no matter when I have done: 

      > stem(theight)
      Error in stem(theight) : stem: x must be numeric

The file looks like this:
 Height
 0.225970
 0.141066
 0.058758
 -0.020346
 -0.095795
 -0.167275
 -0.234242
 -0.296408
 -0.353290
 -0.404554
 -0.450036
 -0.489219
 -0.521996
 -0.548133
 -0.567431
 ... 
 etc

Perhaps there is some manipulation necessary to make the data into a vector, but it isn't obvious to me what to do. 

Thank you for any clue whatsoever.  

Alan Davis
Marianas High School
-- 
adavis at saipan.com                                     1-670-322-6580
    Alan E. Davis,  PMB 30, Box 10006, Saipan, MP 96950-8906, CNMI

I have steadily endeavored to keep my mind free, so as to give up any
hypothesis, however much beloved -- and I cannot resist forming one 
on every subject -- as soon as facts are shown to be opposed to it.  
                                  -- Charles Darwin (1809-1882)

  
 

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