#
# out_eco.writerow(headers_dict)
### for python >= 2.7 comment the above block and uncomment the following line
out_eco.writeheader()
network_file = output_dir + '/' + SRC_NET_FILE
if READ_FILE_NETWORK:
graph = nx.read_graphml(network_file)
net = Network(graph)
print 'connectance = ', net.connectance()
tls = net.get_trophic_levels()
top, top_preds = net.top_predators()
basal, basal_sps = net.basal()
for u, v in net.edges():
if u in basal_sps and v in top_preds and tls[v] == 3:
net.remove_edge(u, v)
print 'new connectance = ', net.connectance()
else:
net = obtain_interactions_network()
net_to_save = net.copy()
nx.write_graphml(net_to_save, network_file)
ecosystem = Ecosystem(net, drawing=False)
ecosystem.initialise_world(True)
#ecosystem.draw_species_distribution()
#network_file = SRC_NET_FILE ## use this when running with networks saved locally in src
#network_file = output_dir + '/new_network_%d.graphml' %(int(task)-1)
if READ_FILE_NETWORK:
graph = nx.read_graphml(network_file)
net = Network(graph)
else:
net = obtain_interactions_network()
print 'connectance = ', net.connectance()
tls = net.get_trophic_levels()
top, top_preds = net.top_predators()
basal, basal_sps = net.basal()
for u,v in net.edges():
if u in basal_sps and v in top_preds and tls[v] == 3:
net.remove_edge(u,v)
print 'new connectance = ', net.connectance()
if not READ_FILE_NETWORK:
net_to_save = net.copy()
nx.write_graphml(net_to_save, network_file)
##############################################
ecosystem = Ecosystem(net, drawing=False)
ecosystem.initialise_world(True)
class NetworkCreator():
'''
classdocs
'''
def __init__(self):
'''
Constructor
'''
self.rnd = Random()
self.rnd_uniform = uniform()
self.net = Network()
# self.invaders = []
def reset_state(self):
self.rnd = Random()
self.rnd_uniform = uniform()
self.net.clear()
def create_niche_model_network(self, S, C, prob=False):
'''
prob = False; whether to create the network following the probabilistic niche model
Niche model
This is an implementation of the niche model
'''
ns = self.rnd_uniform.rvs(size=S+POSSIBLE_INVADERS)
bet = (1/(2*C)) - 1
self.beta_dist = beta(1,bet)
producers = int(math.floor(S*PRIMARY_PRODS))
current_producers = 0
herbivores = int(math.floor(S*HERBIVORY))
current_herbivores = 0
predators = int(math.floor(S*TOP_PREDATORS))
current_predators = 0
#basal_to_top_links = 1 ## New constraint that this must be zero!
while self.net.size() == 0 or not nx.is_connected(self.net.to_undirected()) or current_producers < producers or current_herbivores < herbivores or current_predators < predators: #or max(self.net.get_shortest_chain_length().values()) < 3:
self.net.clear()
# self.invaders = []
basal = None
smallest_n = None
#here we obtain the fundamental niche values for each one of the species in the network
# n, c, r
for i in xrange(1,S+1):
self.net.add_node(i)
self.net.node[i]['n'] = float(ns[i-1]) #self.rnd_uniform.rvs()
self.net.node[i]['r'] = self.beta_dist.rvs() * self.net.node[i]['n']
self.net.node[i]['c'] = self.rnd.uniform((self.net.node[i]['r']/2), min(self.net.node[i]['n'], (1-(self.net.node[i]['r']/2))))
#the original value of c (commented bit) as originally presented in the Nature 2000 paper
#was changed after reading the niche model specification presented in the JAE 2008 paper
#the new specification ensures that the r of all the species always lie within the niche interval [0,1]
#self.net.node[i]['c'] = self.rnd.uniform(self.net.node[i]['r']/2, self.net.node[i]['n'])
self.net.node[i]['invader'] = False
if smallest_n == None or self.net.node[i]['n'] < smallest_n:
smallest_n = self.net.node[i]['n']
basal = i
#if INVASION:
# for i in xrange(S+1, (S+1)+(POSSIBLE_INVADERS)):
## invader = dict()
## invader['n'] = self.rnd_uniform.rvs()
## invader['r'] = self.beta_dist.rvs() * self.net.node[i]['n']
## invader['c'] = self.rnd.uniform(self.net.node[i]['r']/2, self.net.node[i]['n'])
## invader['invader'] = True
#
# self.net.add_node(i)
# self.net.node[i]['n'] = float(ns[i-1]) #self.rnd_uniform.rvs()
# self.net.node[i]['r'] = self.beta_dist.rvs() * self.net.node[i]['n']
# self.net.node[i]['c'] = self.rnd.uniform((self.net.node[i]['r']/2), min(self.net.node[i]['n'], (1-(self.net.node[i]['r']/2))))
# self.net.node[i]['invader'] = False
# self.invaders.append(invader)
self.net.node[basal]['r'] = 0.0
self._create_links_based_on_fundamental_niche()
tls = self.net.get_trophic_levels()
# replacement of links between trophic levels 0 and 3 (does not conform to niches):
top, top_preds = self.net.top_predators()
basal, basal_sps = self.net.basal()
#basal_to_top_links = 0
to_replace = []
for u,v in self.net.edges():
if u in basal_sps and v in top_preds and tls[v] == 3:
#basal_to_top_links += 1
self.net.remove_edge(u,v)
to_replace.append((u,v))
for pair in to_replace:
new_u = pair[1]
while new_u in basal_sps or new_u==pair[1]:
new_u = np.random.randint(1,61) # species indexing starts at 1
self.net.add_edge(new_u, pair[1])
# calculations to check trophic constraints:
current_herbivores = 0
current_producers = 0
current_predators = 0
for k in tls.keys():
if tls[k] == 1:
current_herbivores += 1
elif tls[k] == 0:
current_producers += 1
elif tls[k] == 3:
current_predators += 1
print("replaced %d links" %(len(to_replace)))
return self.net
def _create_links_based_on_fundamental_niche(self, nodes_to_link=None):
#based on the fundamental niche values obtained above we construct the network by adding
#the corresponding links according to the species' niche and feeding range
if nodes_to_link == None:
nodes_to_link = set(self.net.nodes())
for i in self.net.nodes():
if self.net.node[i]['r'] == 0.0:
continue
r_lower_bound = self.net.node[i]['c'] - (self.net.node[i]['r']/2)
r_upper_bound = self.net.node[i]['c'] + (self.net.node[i]['r']/2)
for j in self.net.nodes():
if i not in nodes_to_link and j not in nodes_to_link:
continue
if self.net.node[j]['n'] >= r_lower_bound and self.net.node[j]['n'] <= r_upper_bound:
self.net.add_edge(j,i)
#for disconnected or duplicated nodes
disc_nodes = set()
self_loops = set(self.net.selfloop_edges())
for i in nodes_to_link:
disconnected = False
if self.net.degree(i) == 0:
disconnected = True
elif self.net.in_degree(i) == 1 and (i,i) in self_loops:
# print 'producer with selfloop'
if self.net.out_degree(i) > 1:
self.net.remove_edge(i,i)
else:
disconnected = True
attrs = self.net.node[i]
self.net.remove_node(i)
self.net.add_node(i, attr_dict=attrs)
else:
i_succs = set(self.net.successors(i))
i_predecs = set(self.net.predecessors(i))
for j in self.net.nodes():
j_succs = self.net.successors(j)
j_predecs = self.net.predecessors(j)
if i_succs == j_succs and i_predecs == j_predecs:
disconnected = True
attrs = self.net.node[i]
self.net.remove_node(i)
self.net.add_node(i, attr_dict=attrs)
print 'duplicated node'
break
#we reassign the fundamental niche values to nodes that are disconnected or duplicated
if disconnected:
self.net.node[i]['n'] = self.rnd_uniform.rvs()
self.net.node[i]['r'] = self.beta_dist.rvs() * self.net.node[i]['n']
self.net.node[i]['c'] = self.rnd.uniform(self.net.node[i]['r']/2, self.net.node[i]['n'])
disc_nodes.add(i)
if len(disc_nodes) > 0:
self._create_links_based_on_fundamental_niche(disc_nodes)
return
