[R] Plot error

Joshua Wiley jwiley.psych at gmail.com
Sat Jul 17 17:07:11 CEST 2010

Hi James,

I believe the issue has to do with the values you assigned to 'x' and
'y'.  You call the function c() on seq["value_1"], but you assigned
your data not to 'seq' but to 'test'.  You need to use the variable
name that you assigned your data to (as a side note seq() is a
function, so you should probably avoid using that as name to store
data anyways).  Also you have data in a variable 'test' that has both
rows and columns, so the preferred way to access it is
variablename[rowname/number , columnname/number].  In your case that
would be test[ , "value_1"].  I left the space before the comma blank
to indicate include all rows.  It does technically work in this case
to simply write test["value_1"] but this is prone to error in other
situations.  This is my best guess as to what you want to do:

#Read in Data
#(just to make sure were on the same page)
test <- structure(list(name = structure(c(2L, 1L, 3L),
.Label = c("ben", "bill", "jane"), class = "factor"),
value_1 = 1:3, value_2 = c(4L, 2L, 1L)),
.Names = c("name", "value_1", "value_2"),
class = "data.frame", row.names = c(NA, -3L))

test # print so we can look at it

#Assign columns to variables 'x' and 'y'
x <- test[ , "value_1"]
y <- test[ , "value_2"]

plot(x, y)

#Or using data directly
plot(test[ , "value_1"], test[ , "value_2"])



On Sat, Jul 17, 2010 at 7:50 AM, James Platt <james-platt at hotmail.co.uk> wrote:
> Hi guys,
> I am a newbie to R, so apologies in advance.
> I created this simple table in excel, saved in tab delimited .txt:
> name value_1 value_2
> 1 bill       1            4
> 2 ben      2           2
> 3 jane     3           1
>>test <-read.table("\path\to\file", sep="\t", header=TRUE)
>>x <-c(seq["value_1"])
>>y <-c(seq["value_2"])
> and i get this error
> Error in xy.coords(x, y, xlabel, ylabel, log) :
>  (list) object cannot be coerced to type 'double'
> What does this mean and how do i fix it?
> Thanks for the help, James
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Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles

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