R help - Feb 2005 - Renaming columns in data.frame, inserting/removing columns from data.frame

Hello,

I'm hoping that there is an easier way to rename columns in a data frame 
other than by using the names() assignment, which requires you to type in 
all the column names at once for a data.frame, in the case that I simply 
want to rename a single column in a data frame.

Also, is there an easy way to move columns in a data frame around relative 
to the other columns?

Thanks in advance,
Ken

On Feb 8, 2005, at 1:47 PM, Ken Termiso wrote:
> Hello,
>
> I'm hoping that there is an easier way to rename columns in a data 
> frame other than by using the names() assignment, which requires you 
> to type in all the column names at once for a data.frame, in the case 
> that I simply want to rename a single column in a data frame.
>
If you want to change (or name) only the name in column 12, for example,

names(mydataframe)[12] <- 'new column 12 name'

  will do the trick.

> Also, is there an easy way to move columns in a data frame around 
> relative to the other columns?
You can do this by assigning your rearranged dataframe back to itself 
(carefully):

mydataframe <- mydataframe[c(5:10,1:4),]

Will take the columns 5 through 10 and put them before columns 1 
through 4.  I note "carefully" above because if mydataframe contains, 
for example, 12 columns, the command here would drop columns 11 and 12.

Hope this helps.

Sean

Ken Termiso wrote:
> Hello,
>
> I'm hoping that there is an easier way to rename columns in a data 
> frame other than by using the names() assignment, which requires you 
> to type in all the column names at once for a data.frame, in the case 
> that I simply want to rename a single column in a data frame.
>
names(mydataframe)[column.index]<-"new.name"
> Also, is there an easy way to move columns in a data frame around 
> relative to the other columns?
>
?subset
or
mydataframe[c("column3","column2","column1")]
> Thanks in advance,
> Ken
>
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At 2/8/2005 01:47 PM, Ken Termiso wrote:
>I'm hoping that there is an easier way to rename columns in a data frame
>other than by using the names() assignment, which requires you to type in 
>all the column names at once for a data.frame, in the case that I simply 
>want to rename a single column in a data frame.
This is ugly but it works, and it avoids the use column indices (which I 
find error-prone):

 > aa = data.frame(a=1:6, b=5:10)       # a simple example
 > aa
   a  b
1 1  5
2 2  6
3 3  7
4 4  8
5 5  9
6 6 10

 > names(aa)[names(aa)=="a"] = "c"       # rename
"a" to "c"
 > aa
   c  b
1 1  5
2 2  6
3 3  7
4 4  8
5 5  9
6 6 10
>Also, is there an easy way to move columns in a data frame around relative 
>to the other columns?
Ditto:

 > aa = data.frame(aa["b"],aa["c"])
 > aa
    b c
1  5 1
2  6 2
3  7 3
4  8 4
5  9 5
6 10 6


MHP


-- 
Michael Prager
NOAA Center for Coastal Fisheries and Habitat Research
Beaufort, North Carolina  28516  USA
http://shrimp.ccfhrb.noaa.gov/~mprager/

NOTE: Opinions expressed are personal, not official. No government
endorsement of any product is made or implied.

At 2/8/2005 01:47 PM, Ken Termiso wrote:
>I'm hoping that there is an easier way to rename columns in a data frame
>other than by using the names() assignment, which requires you to type in 
>all the column names at once for a data.frame, in the case that I simply 
>want to rename a single column in a data frame.
This is ugly but it works, and it avoids the use column indices (which I 
find error-prone):

 > aa = data.frame(a=1:6, b=5:10)       # a simple example
 > aa
   a  b
1 1  5
2 2  6
3 3  7
4 4  8
5 5  9
6 6 10

 > names(aa)[names(aa)=="a"] = "c"       # rename
"a" to "c"
 > aa
   c  b
1 1  5
2 2  6
3 3  7
4 4  8
5 5  9
6 6 10
>Also, is there an easy way to move columns in a data frame around relative 
>to the other columns?
Ditto:

 > aa = data.frame(aa["b"],aa["c"])
 > aa
    b c
1  5 1
2  6 2
3  7 3
4  8 4
5  9 5
6 10 6


MHP


-- 
Michael Prager
NOAA Center for Coastal Fisheries and Habitat Research
Beaufort, North Carolina  28516  USA
http://shrimp.ccfhrb.noaa.gov/~mprager/

NOTE: Opinions expressed are personal, not official. No government
endorsement of any product is made or implied.