R help - Mar 2007 - data-frame adding/deleting column

Hallo,

I have got an existing data frame and want to add a new column. The
existing data frame was created like this:
> df <- rbind( c("Fred", "Mary", 4),
c("Fred", "Mary", 7),
+                c("Fred", "Mary", 9), c("Barney",
"Liz", 3),
+                c("Barney", "Liz", 5)
)
> df <- data.frame(df)
> colnames(df) <- c("Father", "Mother",
"Child.Age")
> df
  Father Mother Child.Age
1   Fred   Mary         4
2   Fred   Mary         7
3   Fred   Mary         9
4 Barney    Liz         3
5 Barney    Liz         5

I want to add a column named weddingdate. How does this work and how can
I save the corresponding dates in the cells? (Fred-Mary: 12.12.1980,
Barney-Liz: 3.3.2003)
How can I delet a whole column or row if it is needed?

Thanks, Corinna

This is a slightly different formulation of your problem, but you  
might find it easier to work with:

Start by making a data frame):
	df=data.frame("Father"=c 
("Fred","Fred","Fred","Barney","Barney"),"Mother"=c
("Mary","Mary","Mary","Liz","Liz"),"Child.Age"=c(4,7,9,3,5))

If you want to add a "wedding date" column to this data frame, then
df=data.frame(df,"WeddingDate"=c("December 12th,
1980","December
12th, 1980","December 12th, 1980","March 3rd,
2003","March 3rd, 2003"))

If, for example, you wanted to delete row #4, this is what you could do:
df=data.frame(df[-4,])

Similarly for column #4:
df=data.frame(df[,-4])



Kyle H. Ambert
Graduate Student, Dept. Behavioral Neuroscience
Oregon Health & Science University
ambertk@ohsu.edu





On Mar 26, 2007, at 8:24 AM, Schmitt, Corinna wrote:
Hallo,

I have got an existing data frame and want to add a new column. The
existing data frame was created like this:

df <- rbind( c("Fred", "Mary", 4), c("Fred",
"Mary", 7),
+                c("Fred", "Mary", 9), c("Barney",
"Liz", 3),
+                c("Barney", "Liz", 5) )
df <- data.frame(df)
colnames(df) <- c("Father", "Mother",
"Child.Age")
df
   Father Mother Child.Age
1   Fred   Mary         4
2   Fred   Mary         7
3   Fred   Mary         9
4 Barney    Liz         3
5 Barney    Liz         5

I want to add a column named weddingdate. How does this work and how can
I save the corresponding dates in the cells? (Fred-Mary: 12.12.1980,
Barney-Liz: 3.3.2003)
How can I delet a whole column or row if it is needed?

Thanks, Corinna

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