I’m writting a python script that retrive EUR/USD data prices and display them with plotly on my web browser. Every minutes a new price is received, so I use the add_traces( ) function to update my figure and figure.show( ) to display the result.
But the show function open a new tab every time.
How can I use only 1 tab and update my data on this single tab ?
Hello @tessan,
Welcome to the community!
Every time you use figure.show(), it will automatically open the new figure into a new window.
You’d have to use a callback in order to update the figure’s information.
Isn’t callback a Dash feature? I would prefer to not use Dash if possible because I can’t use Dash in multi-threading. Can you give me a sample code please ?
Here, take a look at this:
It does not really help me.
Here is what I’ve tried so far with Dash framework :
class Chart_renderer:
app = Dash('not main')
app.layout = html.Div([
html.H4('Apple stock candlestick chart'),
dcc.Graph(id="graph"),
dcc.Interval(
id='interval-component',
interval=2*1000, # in milliseconds
n_intervals=0
)
])
df_fixed_length = 50
def __init__(self, df_data):
self.df = df_data
self.fig = go.Figure(
go.Candlestick(
x=self.df.index,
open=self.df['bidopen'],
high=self.df['bidhigh'],
low=self.df['bidlow'],
close=self.df['bidclose']
)
)
def add_new_data(self, new_df_row):
self.df = pd.concat([self.df, new_df_row], axis = 0)
@app.callback(Output("graph", "figure"), Input('interval-component', 'n_intervals'))
def display_candlestick(self, n_intervals):
print('n_interval:', n_intervals)
# if n_intervals == 0 we just display the current self.fig
if n_intervals > 0:
while True:
if self.df_fixed_length < len(self.df):
self.fig.add_trace(
go.Candlestick(
x=[self.df.index[-1]],
open=[self.df['bidopen'].iloc[-1]],
high=[self.df['bidhigh'].iloc[-1]],
low=[self.df['bidlow'].iloc[-1]],
close=[self.df['bidclose'].iloc[-1]]
))
self.df = self.df.drop(self.df.index[0], axis=0)
break
time.sleep(5)
return self.fig
ACCESS_TOKEN = 'xxxx'
conn = fxcmpy.fxcmpy(access_token=ACCESS_TOKEN, log_level='debug', server='demo', log_file='log.txt')
print("Connected to FXCM server!")
# request 50 candlestick prices :
df_prices = conn.get_candles('EUR/USD', period='m1', number=50)
renderer = Chart_renderer(df_prices)
app_thread = Thread(target=renderer.app.run_server, kwargs={'debug':True})
app_thread.start()
# renderer.fig.show()
while(True):
nbr_positions = len(conn.get_open_positions())
if nbr_positions == 0:
current_time = dt.datetime.now()
# Check for updated price data every minutes
if current_time.minute % 1 == 0 :
df_new_price_value = conn.get_candles('EUR/USD', period='m1', number=1)
if(df_new_price_value.index[-1] != renderer.df.index[-1]):
# if price is new we add the new data to the dataframe
renderer.add_new_data(df_new_price_value)
# df_new_price_value = df_new_price_value['bidclose']
# fig = renderer.display_candlestick()
# fig.show()
print("step")
else:
print("trade in process ... ")
But I have this error :
Connected to FXCM server!
Dash is running on http://127.0.0.1:8050/
I think it’s because Dash is not compatible with multi threading
Ok, so question.
Why exactly are you trying to use Dash in a multi-thread?
Also, the figurewidget is not associated with Dash, but python only.
Your real-time data of stocks can be handled a couple of ways with Dash callbacks.
Because I have 2 process that works separatly in my code :
the first retrieves datas from market
the second displays these datas (Dash)
If I use Dash in a single thread, app.server_run() will block my code and I would not be able to retrieve more datas.
Also, I tried Figure widget in my code but it’s not displaying anything.
I’m probably using Dash in the wrong way, do you have a better way to do?
With Dash, you can use dcc.Interval to perform the same task as you while and return the data that way. 
Okey I get it!
If I make all my code inside callbacks method it works.
app = Dash('not main')
app.layout = html.Div([
html.H4('Apple stock candlestick chart'),
dcc.Graph(id="graph"),
dcc.Interval(
id='interval-component',
interval=10*1000, # in milliseconds
n_intervals=0
)
])
df_fixed_length = 50
ACCESS_TOKEN = 'xxx'
conn = fxcmpy.fxcmpy(access_token=ACCESS_TOKEN, log_level='debug', server='demo', log_file='log.txt')
print("Connected to FXCM server!")
df = conn.get_candles('EUR/USD', period='m1', number=50)
fig = go.Figure(
go.Candlestick(
x=df.index,
open=df['bidopen'],
high=df['bidhigh'],
low=df['bidlow'],
close=df['bidclose']
)
)
@app.callback(Output("graph", "figure"), Input('interval-component', 'n_intervals'))
def display_candlestick(n_intervals):
global df
print('n_interval:', n_intervals)
if 0 < n_intervals and df_fixed_length < len(df):
fig.add_trace(
go.Candlestick(
x=[df.index[-1]],
open=[df['bidopen'].iloc[-1]],
high=[df['bidhigh'].iloc[-1]],
low=[df['bidlow'].iloc[-1]],
close=[df['bidclose'].iloc[-1]]
))
df = df.drop(df.index[0], axis=0)
nbr_positions = len(conn.get_open_positions())
if nbr_positions == 0:
current_time = dt.datetime.now()
if current_time.minute % 1 == 0 :
df_new_price_value = conn.get_candles('EUR/USD', period='m1', number=1)
if(df_new_price_value.index[-1] != df.index[-1]):
df = pd.concat([df, df_new_price_value], axis = 0)
return fig
app.run_server(debug=True)
Thanks
Good job! Glad you got it working.