R help - Mar 2008 - Creating plots for all variables in a data frame and printing them with the variable name in the main title

Dear all,

I'm just trying to create plots for all variables in a dataframe (named 
"x") using the following:

png()
apply(x,2,hist)

Just as intended, it produces one plot for each variable. Unfortunately, 
the main title of each graph is "Histogram of newX[,i]" instead of 
"Histogram of name of variable". This makes it impossible to assign
the
graphs to the variables. Is there a way to change this and to make R use 
the correct variable names in the title of the plot?

Thank you very much,

Uli

Try:

x <- data.frame(A=rnorm(100), B=rnorm(100), C=runif(100))
sapply(names(x), function(i)hist(x[,i], main = i))

On 17/03/2008, Uli Kleinwechter <ulikleinwechter at yahoo.com.mx>
wrote:
> Dear all,
>
>  I'm just trying to create plots for all variables in a dataframe
(named
>  "x") using the following:
>
>  png()
>  apply(x,2,hist)
>
>  Just as intended, it produces one plot for each variable. Unfortunately,
>  the main title of each graph is "Histogram of newX[,i]" instead
of
>  "Histogram of name of variable". This makes it impossible to
assign the
>  graphs to the variables. Is there a way to change this and to make R use
>  the correct variable names in the title of the plot?
>
>  Thank you very much,
>
>  Uli
>
>  ______________________________________________
>  R-help at r-project.org mailing list
>  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.
>

-- 
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O

On Mon, 17 Mar 2008, Uli Kleinwechter wrote:
> Dear all,
>
> I'm just trying to create plots for all variables in a dataframe (named
> "x") using the following:
>
> png()
> apply(x,2,hist)
Please don't use apply() on a data frame: you want lapply(x, hist) here.
> Just as intended, it produces one plot for each variable. Unfortunately,
> the main title of each graph is "Histogram of newX[,i]" instead
of
> "Histogram of name of variable". This makes it impossible to
assign the
> graphs to the variables. Is there a way to change this and to make R use
> the correct variable names in the title of the plot?
You need to tell hist() what the title is to be.  I'd just use a loop, 
e.g.

for(xn in names(x)) hist(x[[xn]], title = paste("Histogram of", xn))

but you could use lapply by e.g.

lapply(names(x), function(xn) hist(x[[xn]], title = paste("Histogram
of", xn)))

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

Here is one way:
lapply(1:ncol(x),function(i) hist(x[,i], main =paste("Histogram
of",names(x)[i])))

Bart


Uli Kleinwechter wrote:
> 
> Dear all,
> 
> I'm just trying to create plots for all variables in a dataframe (named
> "x") using the following:
> 
> png()
> apply(x,2,hist)
> 
> Just as intended, it produces one plot for each variable. Unfortunately, 
> the main title of each graph is "Histogram of newX[,i]" instead
of
> "Histogram of name of variable". This makes it impossible to
assign the
> graphs to the variables. Is there a way to change this and to make R use 
> the correct variable names in the title of the plot?
> 
> Thank you very much,
> 
> Uli
> 
> ______________________________________________
> R-help at r-project.org mailing list
> 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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