Data Flow Graph

Definition

A data flow graph shows how data moves through a system.

Nodes represent steps, values, or storage locations.

Edges represent data moving between them.

Example:

Input -> Clean -> Transform -> Output

Data flow graph = graph of where data comes from and where it goes.

---

Simple Example

Suppose a process does this:

number -> add 1 -> multiply by 2 -> result

As a data flow graph:

Input -> Add 1 -> Multiply by 2 -> Result

The output of one step becomes the input to the next step.

Data flow makes step-to-step dependency visible.

---

Nodes As Operations

In many data flow graphs, nodes are operations.

Example:

Read file -> Parse text -> Count words -> Print result

Each node performs a step.

Each edge carries the data needed by the next step.

Operation nodes show what happens to data.

---

Nodes As Values

Sometimes nodes can represent values instead.

Example:

x -> x + 1 -> (x + 1) * 2

Here each node can be read as a value produced during the process.

The graph still shows how one value leads to another.

Data flow can be represented using operation nodes or value nodes.

---

Branching Data Flow

Data can move to more than one later step.

Example:

Input -> Cleaned Data
Cleaned Data -> Summary
Cleaned Data -> Chart

The same intermediate data supports multiple outputs.

Data flow graphs can branch when one result is reused.

---

Final Summary

• A data flow graph shows how data moves through a system.
• Nodes can represent operations, values, or storage locations.
• Edges represent data movement.
• The output of one step can become the input to another.
• Data flow can branch when one result supports multiple later steps.