Question

Does anyone know how to use the subset.ff function in the ff package?

Here is a sample of the data:

col1 col2 col3 col4 col5 col6 col7
    1    1    1    1    1    1    0
    1    1    1    1    1    1    0
  104   11    3    3    1    1 1089
   63   11    2    3    9    1  734
   11    1    3    1    1    1 -609
   11    1    3    1    1    1 -609
   11    1    3    1    1    1 -609

Here is the code:

temp2a <- subset.ff(temp1,temp1$col7!="0") #temp1 is the name of the ff data frame

I get the following error:

Error in `length<-.ffdf`(`*tmp*`, value = 12965531L) : not allowed to change the number of (virtual) columns of ffdf

I am trying to get two ff data frame subsets from the data. One where col7 is equal to 0 and one where col7 is not equal to zero. Does anyone know how to use the subset.ff function or another way to do what I want. I tried looking through the pdf for the ffbase library and all over the web but I couldn’t find any examples.

Cheers again,

Lorcan

Answer 1

what does temp1$col7!="0" give you? Is it like ?subset.ffdf states

an expression, ri, bit or logical ff vector that can be used to index x.

Probably you need to change it to temp1$col7 != 0