从数量列中写入新的相同行

Question

I will explain my problem with an example, we have the following data file in R:

Species   Diameter    Height   Amount

Oak       1           4        2

Beech     2           12       3

Maple     1.5         7.5      1

Oak       2           9        2

So we have 4 columns ( Species , Diameter , Height and Amount ) and several rows with data. Im trying to write a code to transform the data above to this type:

Species   Diameter    Height   
Oak       1           4  

Oak       1           4

Beech     2           12  

Beech     2           12 

Beech     2           12 

Maple     1.5         7.5   

Oak       2           9   

Oak       2           9

So the column Amount is now gone but we obtained several identical rows equal to the initial value in the column Amount .

I have a problem implementing this as a code (I am quite new to R programming). I am thinking in the direction of:

line <- read.csv (file, nrows = 1, header=FALSE)

while{

    algoritm to add the rowns -> data.frame?

    write.csv(dataframe, fileadress)

}

close(file reader)
close (file writer)

I know this is very basic, but I would be very glad with every tip/idea.

Answer 1

In R you should read in the whole file, eg into the variable tab .

Then you can just write tab2 <- tab[ ,-4] .

The -4 means to drop the 4th column, the nothing infront of the comma means 'all rows'.

Then write the whole table to a file.

Note that it is the preferred way to do something like this in R. Loops are only used when really needed.

(You might also want to look at read.table instead of read.csv)

UPDATE:

As GregF notes this is incomplete. I wanted to del this answer but then saw that he had del'ed his too. So please see his comment for what needs to be done to have the repetitions you want.