Subscript out of bounds ошибка

When working with R I frequently get the error message «subscript out of bounds». For example:

# Load necessary libraries and data
library(igraph)
library(NetData)
data(kracknets, package = "NetData")

# Reduce dataset to nonzero edges
krack_full_nonzero_edges <- subset(krack_full_data_frame, (advice_tie > 0 | friendship_tie > 0 | reports_to_tie > 0))

# convert to graph data farme 
krack_full <- graph.data.frame(krack_full_nonzero_edges) 

# Set vertex attributes
for (i in V(krack_full)) {
    for (j in names(attributes)) {
        krack_full <- set.vertex.attribute(krack_full, j, index=i, attributes[i+1,j])
    }
}

# Calculate reachability for each vertix
reachability <- function(g, m) {
    reach_mat = matrix(nrow = vcount(g), 
                       ncol = vcount(g))
    for (i in 1:vcount(g)) {
        reach_mat[i,] = 0
        this_node_reach <- subcomponent(g, (i - 1), mode = m)

        for (j in 1:(length(this_node_reach))) {
            alter = this_node_reach[j] + 1
            reach_mat[i, alter] = 1
        }
    }
    return(reach_mat)
}

reach_full_in <- reachability(krack_full, 'in')
reach_full_in

This generates the following error Error in reach_mat[i, alter] = 1 : subscript out of bounds.

However, my question is not about this particular piece of code (even though it would be helpful to solve that too), but my question is more general:

• What is the definition of a subscript-out-of-bounds error? What causes it?
• Are there any generic ways of approaching this kind of error?

asked Feb 22, 2013 at 19:00

It just means that either alter > ncol( reach_mat ) or i > nrow( reach_mat ), in other words, your indices exceed the array boundary (i is greater than the number of rows, or alter is greater than the number of columns).

Just run the above tests to see what and when is happening.

answered Feb 22, 2013 at 19:07

answered Aug 22, 2017 at 20:31

If this helps anybody, I encountered this while using purr::map() with a function I wrote which was something like this:

find_nearby_shops <- function(base_account) {
   states_table %>% 
        filter(state == base_account$state) %>% 
        left_join(target_locations, by = c('border_states' = 'state')) %>% 
        mutate(x_latitude = base_account$latitude,
               x_longitude = base_account$longitude) %>% 
        mutate(dist_miles = geosphere::distHaversine(p1 = cbind(longitude, latitude), 
                                                     p2 = cbind(x_longitude, x_latitude))/1609.344)
}

nearby_shop_numbers <- base_locations %>% 
    split(f = base_locations$id) %>% 
    purrr::map_df(find_nearby_shops) 

I would get this error sometimes with samples, but most times I wouldn’t. The root of the problem is that some of the states in the base_locations table (PR) did not exist in the states_table, so essentially I had filtered out everything, and passed an empty table on to mutate. The moral of the story is that you may have a data issue and not (just) a code problem (so you may need to clean your data.)

Thanks for agstudy and zx8754’s answers above for helping with the debug.

answered Jan 23, 2019 at 19:03

This came from standford’s sna free tutorial
and it states that …

# Reachability can only be computed on one vertex at a time. To
# get graph-wide statistics, change the value of "vertex"
# manually or write a for loop. (Remember that, unlike R objects,
# igraph objects are numbered from 0.)

ok, so when ever using igraph, the first roll/column is 0 other than 1, but matrix starts at 1, thus for any calculation under igraph, you would need x-1, shown at

this_node_reach <- subcomponent(g, (i - 1), mode = m)

but for the alter calculation, there is a typo here

alter = this_node_reach[j] + 1

delete +1 and it will work alright

answered Mar 5, 2013 at 14:23