[R] adressing dataframes

[John Fitzgerald]

Hi everyone,

I experience some problems with adressing of data.frames when I retrieve
some information for geographical position (ypos, xpos) ot of a MySQL
Database and want to perform some simple statistics. The problem is
adressing the dataframes with a construct like 

rawdata[c(type)] vs. rawdata$TEMPMIN


to retrieve the numerical information and not a string (I want to store the
numerical values in a database for graphical expression)



Code Snippet:

type <- "TEMPMIN"

numbers <-summary(rawdata[c(type)])
numbers2 <- summary(rawdata$TEMPMINIMUM)



Results:


numbers
    TEMPMIN      
 Min.   :-7.200  
 1st Qu.: 2.100  
 Median : 6.200  
 Mean   : 6.588  
 3rd Qu.:11.800  
 Max.   :18.100

> numbers[[1]]
[1] "Min.   :-7.200  "       <<< which is a string



Whereas:

> numbers2
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
 -7.200   2.100   6.200   6.588  11.800  18.100

> numbers2[[1]]
[1] -7.2          <<<< which is a numerical value (and can be easily be
saved in a db)



I've tried some conversions like (as.matrix, as.list, as.data.frame...), but
still, using the c() construct will change the results of summary() to
strings. The same happens with median()....




Kind regards,
 
John Fitzgerald