[R] Plots from categorial data

[Christoph Krammer]

Hello everybody,

Since my first message was caught by the spam filter, I just try to do it
again:

I want to use R to generate plots from categorial data. The data contains
results from OCR scans over images with are preprocessed by different image
filtering techniques. A small sample data set looks as following:

> data <- read.csv("d:/tmp_da/sql_data/filter_d_tool.csv", header=T) 
> data
      ocrtool filter_setting avg.hit.
1  FineReader            2x1    0.383
2  FineReader            2x2    0.488
3  FineReader            3x2    0.268
4  FineReader            3x3    0.198
5  FineReader            4x3    0.081
6  FineReader            4x4    0.056
7        gocr            2x1    0.153
8        gocr            2x2    0.102
9        gocr            3x2    0.047
10       gocr            3x3    0.052
11       gocr            4x3    0.014
12       gocr            4x4    0.002
13      ocrad            2x1    0.085
14      ocrad            2x2    0.094
15      ocrad            3x2    0.045
16      ocrad            3x3    0.050
17      ocrad            4x3    0.025
18      ocrad            4x4    0.009


I now want to draw a plot with the categories (filter_setting) as X axis,
and the avg_hit as Y axis. There should be lines for each ocrtool.

But when I draw a plot, the resulting plot always contains bars, even if I
specify type="n".
> plot(data$filter_setting, data$avg.hit., type="n")

When I only plot the categories, without data, there appear strange grey
(but empty) boxes. 
> plot(data$filter_setting, type="n")

Who do I get a clean white box to draw the different lines in?

Thanks and regards,
 Christoph

---
Christoph Krammer
Student

University of Mannheim
Laboratory for Dependable Distributed Systems A5, 6
68131 Mannheim
Germany