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---
title: graph_partition (v0.26)
description: API reference for qiskit.optimization.applications.ising.graph_partition in qiskit v0.26
in_page_toc_min_heading_level: 2
python_api_type: module
python_api_name: qiskit.optimization.applications.ising.graph_partition
---
<span id="module-qiskit.optimization.applications.ising.graph_partition" />
<span id="qiskit-optimization-applications-ising-graph-partition" />
# qiskit.optimization.applications.ising.graph\_partition
Convert graph partitioning instances into Pauli list Deal with Gset format. See [https://web.stanford.edu/\~yyye/yyye/Gset/](https://web.stanford.edu/~yyye/yyye/Gset/)
**Functions**
| | |
| --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------- |
| [`get_graph_solution`](#qiskit.optimization.applications.ising.graph_partition.get_graph_solution "qiskit.optimization.applications.ising.graph_partition.get_graph_solution")(x) | Get graph solution from binary string. |
| [`get_operator`](#qiskit.optimization.applications.ising.graph_partition.get_operator "qiskit.optimization.applications.ising.graph_partition.get_operator")(weight\_matrix) | Generate Hamiltonian for the graph partitioning |
| [`objective_value`](#qiskit.optimization.applications.ising.graph_partition.objective_value "qiskit.optimization.applications.ising.graph_partition.objective_value")(x, w) | Compute the value of a cut. |
### get\_graph\_solution
<Function id="qiskit.optimization.applications.ising.graph_partition.get_graph_solution" github="https://github.com/qiskit-community/qiskit-aqua/tree/stable/0.9/qiskit/optimization/applications/ising/graph_partition.py" signature="get_graph_solution(x)">
Get graph solution from binary string.
**Parameters**
**x** (*numpy.ndarray*) binary string as numpy array.
**Returns**
graph solution as binary numpy array.
**Return type**
numpy.ndarray
</Function>
### get\_operator
<Function id="qiskit.optimization.applications.ising.graph_partition.get_operator" github="https://github.com/qiskit-community/qiskit-aqua/tree/stable/0.9/qiskit/optimization/applications/ising/graph_partition.py" signature="get_operator(weight_matrix)">
Generate Hamiltonian for the graph partitioning
**Notes**
**Goals:**
1 separate the vertices into two set of the same size 2 make sure the number of edges between the two set is minimized.
**Hamiltonian:**
H = H\_A + H\_B H\_A = sum\_\{(i,j)in E}\{(1-ZiZj)/2} H\_B = (sum\_\{i}\{Zi})^2 = sum\_\{i}\{Zi^2}+sum\_\{i!=j}\{ZiZj} H\_A is for achieving goal 2 and H\_B is for achieving goal 1.
**Parameters**
**weight\_matrix** (*numpy.ndarray*) adjacency matrix.
**Returns**
operator for the Hamiltonian float: a constant shift for the obj function.
**Return type**
[WeightedPauliOperator](qiskit.aqua.operators.legacy.WeightedPauliOperator "qiskit.aqua.operators.legacy.WeightedPauliOperator")
</Function>
### objective\_value
<Function id="qiskit.optimization.applications.ising.graph_partition.objective_value" github="https://github.com/qiskit-community/qiskit-aqua/tree/stable/0.9/qiskit/optimization/applications/ising/graph_partition.py" signature="objective_value(x, w)">
Compute the value of a cut.
**Parameters**
* **x** (*numpy.ndarray*) binary string as numpy array.
* **w** (*numpy.ndarray*) adjacency matrix.
**Returns**
value of the cut.
**Return type**
float
</Function>