On May 15, 2015, at 9:55 AM, Liao, Hongsheng <[email protected]> wrote:
> I know how to make one-row header for a data frame using "colnames". Is
> there any function to insert sub-header between the first row of the data and
> the header? Thanks
The elements of a data frame's columns are all of the same type. Inserting an
extra row with character values would coerce the entire column to be of type
character:
myDf <- data.frame(a=c(1:3),b=letters[1:3], C=LETTERS[1:3],
stringsAsFactors=FALSE)
sapply(myDf, class)
a b C
"integer" "character" "character"
myDf <- rbind(c("text1", "text2", "text3"), myDf)
myDf
a b C
1 text1 text2 text3
2 1 a A
3 2 b B
4 3 c C
sapply(myDf, class)
a b C
"character" "character" "character"
In addition, you shouldn't be thinking about the "header" as being a textual
description anyway: the colname is actually much like a variable name, a label
to identify a column. If you think of an Excel file (I think this is where your
question is coming from), the names are the A, B ... Z, AA, AB ... names. It
just so happens that R can construct column names from data it finds in a
"header row". But they are _attributes_ of the data frame, not part of the
contents. However you can look at the attributes ...
attributes(myDf)
$names
[1] "a" "b" "C"
$row.names
[1] 1 2 3 4
$class
[1] "data.frame"
attributes(myDf)$names
[1] "a" "b" "C"
... and you can add additional attributes:
attributes(myDf)$subheaders <- c("text1", "text2", "text3")
attributes(myDf)
$names
[1] "a" "b" "C"
$row.names
[1] 1 2 3 4
$class
[1] "data.frame"
$subheaders
[1] "text1" "text2" "text3"
Hope this helps.
Boris
>
> Hongsheng (Hank) Liao, PhD.
> Lab Manager
> Center for Quantitative Fisheries Ecology
> Old Dominion University
> 757-683-4571
>
>
>
>
> [[alternative HTML version deleted]]
>
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