[R] Create histogram from data matrix

[jim holtman]

here is one way:

> mydata <- data.frame(observ=sample(1:10,20,TRUE), value=sample(1:6,20,TRUE))
>
> mydata
   observ value
1       3     6
2       4     2
3       6     4
4      10     1
5       3     2
6       9     3
7      10     1
8       7     3
9       7     6
10      1     3
11      3     3
12      2     4
13      7     3
14      4     2
15      8     5
16      5     5
17      8     5
18     10     1
19      4     5
20      8     3

> hist(rep(mydata$value, mydata$observ))


On Fri, Apr 17, 2009 at 10:59 AM, Paul Warren Simonin
<Paul.Simonin at uvm.edu> wrote:
> Hello!
>  Thanks for reading this request for assistance. I have a question regarding
> creating a histogram-like figure from data that are not currently in the
> correct format for the "hist" command.
>  Specifically, my data have been processed and are in a matrix with columns
> containing the variables of interest and separate columns containing the
> number of times this variable was observed (counts). This data frame/matrix
> is rather large (1600 rows), and there are multiple rows corresponding to
> the same variable level (e.g., "temperature=8, 5 observations" in one row,
> then the next: "temperature=8, 9 observations", and so on). In other words,
> the data are not one long vector R can read and plot as a histogram, nor are
> they condensed. My goal is to create a figure in which one axis is bins
> (e.g., temperature values) and the other is number of observations in this
> bin (e.g., number of organisms seen).
>  My question is: Is there a way R can be told to read my data to create a
> plot like that I desire? So far I have tried several options, including bar
> plots with no success.
>
>  If there is no way to do this with my data as the are currently arrange, is
> there an efficient way to re-arrange them?
>
> Thanks a lot for any assistance or advice!
>
> Sincerely,
> Paul Simonin
>
>
> --
> Paul W. Simonin
> Graduate Research Assistant, MS Program
> Vermont Cooperative Fish and Wildlife Research Unit
> The Rubenstein School of Environment and Natural Resources
> University of Vermont
> 81 Carrigan Dr.
> Burlington, VT 05405
> Ph:802-656-3153
>
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?