# graph.data.frame

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##### Creating igraph graphs from data frames

This function creates an igraph graph from one or two data frames containing the (symbolic) edge list and edge/vertex attributes.

Keywords
graphs
##### Usage
graph.data.frame(d, directed=TRUE, vertices=NULL)
##### Arguments
d
A data frame containing a symbolic edge list in the first two columns. Additional columns are considered as edge attributes.
directed
Logical scalar, whether or not to create a directed graph.
vertices
A data frame with vertex metadata, or NULL. See details below.
##### Details

graph.data.frame creates igraph graphs from one or two data frames. It has two modes of operatation, depending whether the vertices argument is NULL or not.

If vertices is NULL, then the first two columns of d are used as a symbolic edge list and additional columns as edge attributes. The names of the attributes are taken from the names of the columns.

If vertices is not NULL, then it must be a data frame giving vertex metadata. The first column of vertices is assumed to contain symbolic vertex names, this will be added to the graphs as the name vertex attribute. Other columns will be added as additional vertex attributes. If vertices is not NULL then the symbolic edge list given in d is checked to contain only vertex names listed in vertices.

Typically, the data frames are exported from some speadsheat software like Excel and are imported into R via read.table, read.delim or read.csv.

##### Value

• An igraph graph object.

##### Note

NA elements in the first two columns d are replaced by the string NA before creating the graph. This means that all NAs will correspond to a single vertex.

NA elements in the first column of vertices are also replaced by the string NA, but the rest of vertices is not touched. In other words, vertex names (=the first column) cannot be NA, but other vertex attributes can.

##### concept

Data frame

graph.constructors and graph.formula for other ways to create graphs, read.table to read in tables from files.

##### Aliases
• graph.data.frame
##### Examples
## A simple example with a couple of actors
## The typical case is that these tables are read in from files....
actors <- data.frame(name=c("Alice", "Bob", "Cecil", "David",
"Esmeralda"),
age=c(48,33,45,34,21),
gender=c("F","M","F","M","F"))
relations <- data.frame(from=c("Bob", "Cecil", "Cecil", "David",
"David", "Esmeralda"),
to=c("Alice", "Bob", "Alice", "Alice", "Bob", "Alice"),
same.dept=c(FALSE,FALSE,TRUE,FALSE,FALSE,TRUE),
print(g, e=TRUE, v=TRUE)