I have seen multiple demos to show how to use extendData for streaming data in real-time, but all the examples were with scatterplots. I’m not sure if it would work with heatmap.
I want to stream a heatmap in real-time from local text files on my computer. These files are generated by software every 5 seconds. So, my app will check this folder to find which file was added to the folder. Then it would load the file and assign the new values for xnew, ynew, and znew.
xnew is the timestamp, ynew and znew are other physical properties at each timestamp. Then return [dict(x=[xnew], y=[ynew], z=[znew])] to “extendData” of the figure.
It appeared that the app was able to load the first and second files because I can see a change in the x-axis. However, as the third file was generated in the folder, it seems that the heatmap did only update the z values but not the x-axis. It looked like the heatmap was stuck at the same timestamp. I have printed out the new, ynew, and znew values and confirmed that the app was able to find the newly generated file and load it. But I’m not sure why the heatmap did not update the x-axis.
I’m not sure what I have done incorrectly here. Have any of you done this before?
@Emil, @Emmanuelle, @brad would you advise me on this issue, please?
figure=dict( data=[{'x': [], 'y': [],'z':[], 'type':'heatmap', 'colorscale':jet_scale, 'zmin':-5, 'zmax':5, 'zsmooth':'best'}],
layout=dict(width=1900, height=1000, xaxis1=dict(domain=[0,0.97], anchor='y1', ),
yaxis=dict(titile='<b> Depth (ft)</b>', range=[16000,9000])))
#%%%
'''
Define Dash Layout
'''
# app = dash.Dash(__name__)
app=Dash(__name__, prevent_initial_callbacks=True)
app.layout = html.Div(
[
dcc.Graph(id = 'live-graph',
# animate = True,
figure=dict(figure)),
dcc.Interval(
id = 'interval',
interval = 10*1000, # 10sec
n_intervals = 0
),
dcc.Store(
id='data-storage', data={}
),
html.Div(id='hidden-div'),
]
)
@app.callback(
[
Output('live-graph', 'extendData')],
[
Input('interval','n_intervals'),
]
)
def update_data(n_interval):
xnew=[]
ynew=[]
znew=[]
path=r'E:\Hess\LAS\Test'
fn=os.listdir(path)
if len(fn)==0:
return [dict(x=xnew, y=ynew, z=znew)]
else:
idx=int(n_interval-1)
print(f'length of fn is {len(fn)}')
print(f'The value of idx is {idx}')
f=fn[idx]
full_path=os.path.join(path,f)
new_data=function_to_load_text_file(full_path)
print(f'new data is {new_data}')
xnew=new_data.columns
ynew=new_data.index
znew=new_data.values
print(f'xnew is {xnew}')
print(f'ynew is {ynew}')
print(f'znew is {znew}')
return [dict(x=[xnew], y=[ynew], z=[znew])]
