R data types: data.frames

I've been harping on about R programming basics - but a solid foundation is essential as you progress in a language. Review clears up misconceptions you may have picked up along the way. Let's spend a moment reviewing data.frames...

Data frames are like spreadsheets

Vectors, matrices, and arrays can only contain one data structure: numeric, character, logical, and so on. An R list and a data.frame may contain multiple structures. Lists keep the relationships between data sets, data.frames present that information in a row/column format. For example...

> numericVector <- c(1,2,3,4,5,6)

> characterVector <- c("twas","brillig","and","the","slithey","toves")

> monthVector<- month.abb[1:6] # e.g. jan, feb, mar, apr, may, jun

> I.am.a.dataframe <- data.frame(numericVector,characterVector,monthVector)

> I.am.a.dataframe
  numericVector characterVector monthVector
1             1            twas         Jan
2             2         brillig         Feb
3             3             and         Mar
4             4             the         Apr
5             5         slithey         May
6             6           toves         Jun
        

So I.am.a.dataframe shows how the three vectors have been placed in columns in the data.frame. We should look at the structure as well...

> str(I.am.a.dataframe)

'data.frame':	6 obs. of  3 variables:
 $ numericVector  : num  1 2 3 4 5 6
 $ characterVector: chr  "twas" "brillig" "and" "the" ...
 $ monthVector    : chr  "Jan" "Feb" "Mar" "Apr" ...
        

This shows that numericVector is a column of numbers. characterVector and monthVector are columns of characters. Incidentally, obs is another term for rows. variables is another term for columns.

Want to know more?

I publish a weekly video series on the R language. Here's a session on data.frames...

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