[R] Periods instead of spaces in dataframe names?

[John Fox]

Dear Tom,

When you read the data into a data frame via read.csv, the character 
strings in the first row of the data file, which you've indicated is to be 
interpreted as a header, are used for column names; in the process, blanks 
are converted to periods, since nonstandard names including blanks are more 
difficult to deal with; names(df[13]) just returns the name of column 13 in 
the data frame. You could use the gsub function to recover the blanks -- 
something like gsub("\\."," ", names(df[2])). Alternatively, you could 
specify the argument check.names=FALSE to read.csv to avoid substituting 
periods for blanks in the first place, but this probably isn't a good idea. 
See ?read.csv for details.

I hope that this helps,
  John


At 09:33 AM 2/11/2003 -0700, Tom Arnold wrote:
>Basic question:
>when I use names() to extract the name of a dataframe element, why does it
>have "." instead of " " between words?
>
>Context:
>I'm importing a CSV file of survey results for analysis. I read them like
>this:
>
>df <- read.csv("surveydata.csv",nrows=40,header=TRUE,
>                na.string=c("N/A",""),comment.char="",strip.white=TRUE)
>
>To do a summary of the responses to a question, I can now do something like
>this:
>
>table(df[13])
>
>  1  2  3  4
>13 13  4  2
>
>and can then do a barplot with:
>barplot(table(df[13])))
>
>Which is fine. But since the first row of my data file includes the questions
>themselves, I want to use those questions as chart titles, like this:
>
>barplot(table(df[13]),main=names(df[13]))
>
>This gives an unexpected result: the title has a "." where every space should
>be between words, like this: "How.many.cats.do.you.own"
>
>I can't figure out why, or how to get spaces instead of "." to show up. I've
>tried using gsub but without success, to substitute " " for "."
>
>I'm think I'm confused about something fundamental here, and hope someone has
>the patience to enlighten me. I confess to a being a bit vague in my
>understanding of R's handling of arrays, dataframes, and vectors. My
>background is in C programming and I keep looking for a "string"...
>
>Thank you very much. Please reply or copy me directly if you respond.
>
>Tom Arnold
>Managing Partner, Summit Media Partners LLC
>Visit our web site at http://www.summitmediapartners.com
>
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>R-help at stat.math.ethz.ch mailing list
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-----------------------------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario, Canada L8S 4M4
email: jfox at mcmaster.ca
phone: 905-525-9140x23604
web: www.socsci.mcmaster.ca/jfox
-----------------------------------------------------