[R] hist() and database

[Uwe Ligges]

jcb wrote:

> Hello,
> 
> I'm a new R user and I'm having a little trouble getting started. I'm 
> hoping
> someone can help me out. I read numbers (integer) from a SQL database. 
> Some calculations as mean()are possible but hist() give an error. Here 
> are the commands:
> 
> library(RMySQL)
> Loading required package: DBI
>  > con <- dbConnect(dbDriver("MySQL"), dbname = "test")
>  > dbListTables(con)
> [1] "individu"
> res <- dbSendQuery(con,"select taille from individu")
>  > data <- fetch(res,-1)
>  > data
>   taille
> 1     184
> 2     175
> 3     189
> 4     173
> 5     169
> 6     175
> 7     164
> 8     190
> 9     174
> 10    184
> 11    168
> 12    179
> 13    174
> 14    163
> 15    175
> 16    176
> 17    190
> 18    172
> 19    178
> 20    173
>  > mean(data)
> taille
> 176.25
>  > hist(data)
> Error in hist.default(data) : `x' must be numeric
> 
> What can I do to draw the histogram ?

data is a data.frame, instead use:
   hist(data$taille)

Uwe Ligges


> Thanks for your time
> 
> JC Bartier
> 
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