[R] Histogram of character elements

[Ben Tupper]

Hi again,

I'm sort of pre-coffee still, but does this do it?  The data frame only has one variable, a factor where the order of the levels is specified.

library(lattice)
group   <- c("a", "b", "c", "d", "e")
freq    <- c(1, 2, 2, 5, 3)
x       <- rep(group, freq)
df      <- data.frame(group = factor(x, levels = c("d", "a", "b", "c", "e")) )
histogram(~ group, data = df)

As far as super-grouping the answer is likely yes, but without details and an example (and coffee) I'm at a loss.   I suggest getting a your hands on a copy of https://www.r-project.org/doc/bib/R-books_bib.html#R:Sarkar:2008 <https://www.r-project.org/doc/bib/R-books_bib.html#R:Sarkar:2008> It's really worth it if you plan to spend time with lattice.

Cheers,
Ben 


> On Jun 7, 2018, at 7:02 AM, Luigi Marongiu <marongiu.luigi using gmail.com> wrote:
> 
> also, with this approach, I need to re-arrange the data. Is it
> possible to work directly on a dataframe?
> On Thu, Jun 7, 2018 at 12:48 PM Ben Tupper <btupper using bigelow.org> wrote:
>> 
>> Hi,
>> 
>> Is this what you are after?
>> 
>> group <- c("a", "b", "c", "d", "e")
>> freq <-c(1, 2, 2, 5, 3)
>> x = rep(group, freq)
>> barplot(table(x))
>> 
>> Cheers,
>> Ben
>> 
>> 
>> 
>> On Jun 7, 2018, at 6:00 AM, Luigi Marongiu <marongiu.luigi using gmail.com> wrote:
>> 
>> Dear all,
>> I have a dataframe with a column representing the names of the
>> elements (a, b, etc) and one with their frequencies.
>> How can I plot the frequencies so that each element has an associated
>> frequency value?
>> I have been thinking of a histogram, but I have found it difficult to
>> implement. I have tried the following:
>> 
>> group <- c("a", "b", "c", "d", "e")
>> freq <-c(1, 2, 2, 5, 3)
>> df <- data.frame(group, freq, stringsAsFactors = FALSE)
>> hist(df$freq)
>> library(lattice)
>> histogram( ~ df$group)
>> histogram( ~ as.factor(df$group))
>> histogram(df$freq ~ as.factor(df$group))
>> 
>> hist(df$freq) returns a histogram in which the values 1 and 2 appear 3
>> times, the values 3 and 5 appear once and 4 never. This is not what I
>> wanted; I want instead a graph telling me that a appears once, b twice
>> etc.
>> 
>> histogram( ~ df$group) gives the error:
>> Error in hist.default(as.numeric(x), breaks = breaks, plot = FALSE,
>> include.lowest = include.lowest,  :
>> negative length vectors are not allowed
>> 
>> histogram( ~ as.factor(df$group)) and histogram(df$freq ~
>> as.factor(df$group)) report all groups on the x axis (that is good)
>> but all at 20% level.
>> 
>> What am I missing?
>> Thank you.
>> 
>> --
>> Best regards,
>> Luigi
>> 
>> ______________________________________________
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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.
>> 
>> 
>> Ben Tupper
>> Bigelow Laboratory for Ocean Sciences
>> 60 Bigelow Drive, P.O. Box 380
>> East Boothbay, Maine 04544
>> http://www.bigelow.org
>> 
>> Ecological Forecasting: https://eco.bigelow.org/
>> 
>> 
>> 
>> 
>> 
> 
> 
> -- 
> Best regards,
> Luigi
> 

Ben Tupper
Bigelow Laboratory for Ocean Sciences
60 Bigelow Drive, P.O. Box 380
East Boothbay, Maine 04544
http://www.bigelow.org

Ecological Forecasting: https://eco.bigelow.org/






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