Search code examples
rmatrixsumxtszoo

sum only the negative values in a row from an xts-object

I have an xts-object and I want to sum only the negative values in the first row.

The code

sum(test[test<0])

gives me the error

Error in `[.xts`(test, test < 0) : 'i' or 'j' out of range

but 

sum(test[1],na.rm=TRUE)

works, but then I have the sum of all the values, not just the negative ones:

[1] -0.9786889

Without giving an example of data yet, does anybody know why this simple code doesnt work?

The dimension of the xts-object is > dim(test) is 216 39.

Solution

  • There is a chance that this is related to the open xts issue here ---> here

    It appears that xts objects cannot be subset in this manner. Instead, you should use coredata(), an xts function that treats the "core data" as a matrix.

    It's a little messy but:

    sum(coredata(test)[1,][coredata(test)[1,] < 0]

    should work. If you wanted to do this for all rows, you would need to use something like apply() or a for loop.