  Here is the Python code that calculates the average elemental stress on a given volume using the pydpf-core library:
```
from pydpf_core import *

# Create a model targeting a given result file
model = Model("result.res")

# Get all node IDs in the model
node_ids = model.get_node_ids()

# Find the minimum amount of surrounding elements to get a minimum volume
min_elements = 10

# Read the volume by element
elements_volume = model.elements_volume(min_elements)

# Find the minimum list of elements by node to get the volume check
volume_check = elements_volume.min_elements_by_node()

# Create a workflow to compute equivalent stress averaged on elements
workflow = Workflow("equivalent_stress_averaged_on_elements")

# Apply dot product seqv.volume
workflow.add_operator("dot_product", "seqv.volume")

# Sum up those on the list of elements
workflow.add_operator("sum", "elements_volume")

# Divide this sum by the total volume on these elements
workflow.add_operator("divide", "sum", "total_volume")

# Plot equivalent elemental stress and volume averaged elemental equivalent stress
workflow.add_operator("plot", "equivalent_stress_averaged_on_elements", "volume_averaged_equivalent_stress")

# Use the operator with the same algorithm that has been implemented
workflow.add_operator("use_operator", "equivalent_stress_averaged_on_elements", "volume_averaged_equivalent_stress")

# Run the workflow
workflow.run()
```
Note that this code assumes that the result file contains the necessary data for computing the equivalent stress and volume averaged elemental equivalent stress. If the result file does not contain this data, you will need to modify the code to include the necessary operators and inputs.