Adding Vertical Line - Conditional On Function Output - No dropdowns or UI Elements

📊 Plotly Python
1

Hi, I’m the guy that made this example:

Example Candlestick Chart From CSV File

I’m trying to add vertical lines AFTER the chart is drawn, from the output of another function that does some computation, then creates a list of x index numbers.

I can do it on a static example, like the one I made above – but when I want to add lines, even when I pass the list into my abstracted function for the figure:

def myCandleChart(myInputData, myResults): # Adding results to pass final result list...
	myFig = make_subplots(rows=2, row_heights=[0.70,0.30], cols=1, shared_xaxes=True, vertical_spacing=0.02) # Heights must add up to 1

	# Plotly Chart
	myFig.add_trace(
		go.Candlestick(
			x=myInputData['BarTimestamp'],
			open=myInputData['Open'],
			high=myInputData['High'],
			low=myInputData['Low'],
			close=myInputData['Close'],
			name="Price"),
			row=1, col=1
		)
	# Add Indicator subplot with go.Scatter - works, Line is deprecated 
	myFig.add_trace(go.Scatter(x=myInputData['BarTimestamp'], y=myInputData['Indicator'], name="Indicator", line=dict(color='rgb(235,140,52)')), row=2, col=1) # Dark orange
	# Remove default rangeslider
	myFig.update_layout(xaxis_rangeslider_visible=False)
	# Background color
	myFig.update_layout(plot_bgcolor='rgb(0,0,0)')
	# Axes line color
	myFig.update_xaxes(showline=True, linewidth=1, linecolor='dimgray')
	myFig.update_yaxes(showline=True, linewidth=1, linecolor='dimgray')
	# Tick value display format - yaxis<num> is for subplots
	myFig.update_layout(yaxis={"tickformat" : ','}, yaxis2={"tickformat" : '.2f'}) # Displays thousands,hundreds without scientific 'K' notation
	# Grid line color
	myFig.update_xaxes(showgrid=True, gridwidth=1, gridcolor='dimgray')
	myFig.update_yaxes(showgrid=True, gridwidth=1, gridcolor='dimgray')
	# Adjusting font sizes
	myFig.update_layout(
		font=dict(
			family="Microsoft Sans Serif", # Font needs to be installed on system to be accessible
			size=12, color='rgb(160,166,184)' # Light Gray
		)
	)
	# Chart title
	myFig.update_layout(title="BTCUSD 5min", title_x=0.5, yaxis_title="Price", yaxis2_title="Indicator")
	# Legend Background Transparent Color, 'Paper' background color - plot canvas, sets pan enabled on load
	myFig.update_layout(legend=dict(bgcolor='rgba(0,0,0,0)'), paper_bgcolor='rgb(12,12,12)', dragmode='pan')
	
	# Got hits? Draw lines...
	if len(myResults) > 0:
		# Debug
		print("< Candle Chart Func > Inside result status IF block - firing line drawing FOR loop... \n")
		# Add vertical lines for index matches
		for myLine in myResults:
			myFig.add_vline(x=myLine, line=dict(color='rgb(52,183,235)', width=2, dash='dot')) # Light blue
	
	# Debug
	print("< Candle Chart Func > Length of result status: " + str(len(myResults)))
	
	return myFig

I have no issues with the chart being drawn the first time - works great like in my example post, just not sure why it won’t add the lines when the myResults list is populated with x axis values… I know that the IF block is working because of the debug output:

CandleChartDebugOutput
CandleChartDebugOutput900×98 4.74 KB

So I’m a bit stumped as to why it won’t do this… I’d appreciate any simple example in reply as I’m still learning.

Thanks!

2

I mis-spoke at the start of my post – I want to add lines when this chart function is called, the original pass works – but when I have lines to draw the next chart refresh doesn’t show any.

I realize the earlier post seemed like I was trying to add something after the chart itself had been done, which isn’t the case.