R help - Oct 2015 - Barplot - Beginners Question

Hi!

According to this I tried to create a barplot:

https://de.wikibooks.org/wiki/GNU_R:_barplot

Input Data (Tab delimeted)

Range   Anzahl  Prozent
36-40   12      1.92
41-45   21      3.36
46-50   48      7.68
51-55   87      13.92
56-60   92      14.72
61-65   131     20.96
66-70   67      10.72

I read the table using this command:
> datentabelle <- read.table( "stats-test.txt", header = TRUE,
sep = "\t", dec = ".", row.names=1)
> datentabelle
      Anzahl Prozent
36-40     12    1.92
41-45     21    3.36
46-50     48    7.68
51-55     87   13.92
56-60     92   14.72
61-65    131   20.96
66-70     67   10.72
71-75     52    8.32
76-80     25    4.00
> is.data.frame(datentabelle)
[1] TRUE
>
Looking ate the table it looks like VADeaths

Then I try to plot as described in wikibooks
> barplot(datentabelle[,1], main= "Altersverteilung")
The plot I get looks lie that using VADeaths with one difference:
I do not ret the rownames in my table as labels for the bars

So what am I missing?

I expect something like I get from
> barplot(VADeaths[,1], main= "Altersverteilung")
Jutta



--
http://www.witch.westfalen.de

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On 04/10/2015 3:31 PM, Jutta Wrage wrote:
> Hi!
> 
> According to this I tried to create a barplot:
> 
> https://de.wikibooks.org/wiki/GNU_R:_barplot
> 
> Input Data (Tab delimeted)
> 
> Range   Anzahl  Prozent 36-40   12      1.92 41-45   21      3.36 
> 46-50   48      7.68 51-55   87      13.92 56-60   92      14.72 
> 61-65   131     20.96 66-70   67      10.72
> 
> I read the table using this command:
>> datentabelle <- read.table( "stats-test.txt", header =
TRUE, sep
>> = "\t", dec = ".", row.names=1) datentabelle
> Anzahl Prozent 36-40     12    1.92 41-45     21    3.36 46-50
> 48    7.68 51-55     87   13.92 56-60     92   14.72 61-65    131
> 20.96 66-70     67   10.72 71-75     52    8.32 76-80     25
> 4.00
>> is.data.frame(datentabelle)
> [1] TRUE
>> 
> 
> Looking ate the table it looks like VADeaths
> 
> Then I try to plot as described in wikibooks
> 
>> barplot(datentabelle[,1], main= "Altersverteilung")
> 
> The plot I get looks lie that using VADeaths with one difference: I
> do not ret the rownames in my table as labels for the bars
> 
> So what am I missing?
Your data is a dataframe, VADeaths is a matrix.  For some dim
historical reason, pulling a column from a matrix keeps the row names,
but pulling a column from a dataframe doesn't.

You'll get what you want if you use as.matrix(datentabelle)[,1]
instead of datentabelle[,1].

Duncan Murdoch
> 
> I expect something like I get from
>> barplot(VADeaths[,1], main= "Altersverteilung")
> 
> Jutta
> 
> 
> 
> -- http://www.witch.westfalen.de
> 
> 
> 
> ______________________________________________ R-help at r-project.org
> mailing list -- To UNSUBSCRIBE and more, see 
> 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.
> 
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On Oct 4, 2015, at 7:39 PM, Duncan Murdoch <murdoch.duncan at gmail.com>
wrote:
> You'll get what you want if you use as.matrix(datentabelle)[,1]
> instead of datentabelle[,1].
This happens to work in this particular case, but fails if the data frame
contains text columns.
Example:
   datentabelle <- cbind(datentabelle, text = sample(letters,
nrow(datentabelle)))
   barplot(as.matrix(datentabelle)[,1])
   R>  Error in -0.01 * height : non-numeric argument to binary operator

Therefore I would get the row names from your data frame with
rownames(datentabelle), and use them as the names.arg argument of barplot():

  barplot(datentabelle[,1], names.arg=rownames(datentabelle))

Cheers,
Boris