import json
# Create some data
data ={
  "mat" :[[1,2,3],[4,5,6],[7,8,9]],
  "threshold": 0.5
}

# Write to JSON
with open( 'data.json', 'w') as f:
  json.dump(data, f)

# Read from JSON
with open( 'data.json', 'r') as f:
  data_read = json. load(f)

print (data_read)