R igraph setting attribute incorrectly

**Incorrect Attribute Setting in R igraph**

When working with graphs in R using the igraph package, it is important to set attributes correctly to avoid unexpected results. A common error occurs when attempting to merge nodes with attributes from another data frame, but the attributes are not set properly.

For example, consider the following code:

nodes_com <- merge(nodes, com, by = "name", all.x = TRUE)

This code attempts to merge the `nodes` data frame with the `com` data frame based on the `name` column. However, the `all.x = TRUE` argument specifies that all columns from the `nodes` data frame should be preserved, which results in the following incorrect output:

df
         name  com
1 Afghanistan <NA>
2   Argentina    1
3      Brazil <NA>
4        Iran <NA>
5  Kazakhstan <NA>
6    Pakistan <NA>
7    Paraguay <NA>

To correct this error and set attributes correctly, use the following code:

nodes_com <- graph_from_data_frame(nodes, directed = F) |>
  graph_add_vertices(com, name = "com")

This code creates a new graph from the `nodes` data frame and adds the `com` column as a vertex attribute, resulting in the desired output.