Plotly markers symbols

Anvil Q&A
#1

Can someone explain why plotly correctly displays markers symbols up to 19 markers (first plot) and then, when markers are 20 or higher, markers symbols are not shown anymore (second plot)?

Markers texts are working, only symbols don’t.

2019-08-14_13-00-42
2019-08-14_13-00-42.png979×879 46 KB

The code is straightforward:

  def form_show(self, **event_args):
    """This method is called when the HTML panel is shown on the screen"""
    x = ['Rating iniziale', 'Game 1', 'Game 2', 'Game 3', 'Game 4', 'Game 5', 'Game 6', 'Game 7', 'Game 8', 'Game 9', 'Game 10', 'Game 11', 'Game 12', 'Game 13', 'Game 14', 'Game 15', 'Game 16', 'Game 17', 'Game 18', 'Game 19', 'Game 20', 'Game 21']
    y = [1251, 1270, 1270, 1259, 1259, 1247, 1247, 1270, 1270, 1297, 1297, 1297, 1284, 1284, 1284, 1269, 1244, 1228, 1228, 1213, 1203, 1223]
    symbols = [0, 0, 0, 4, 0, 0, 0, 17, 0, 17, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, 17]
    colors = ['Black', 'DarkGreen', 'Black', 'DarkRed', 'Black', 'Black', 'Black', 'DarkGreen', 'Black', 'DarkGreen', 'Black', 'Black', 'DarkRed', 'Black', 'Black', 'Black', 'Black', 'Black', 'Black', 'Black', 'Black', 'DarkGreen']
    sizes = [10, 15, 10, 15, 10, 10, 10, 15, 10, 15, 10, 10, 15, 10, 10, 10, 10, 10, 10, 10, 10, 15]
    markers_texts = ['', 'Pet! Bravoooo!!', '', 'Worst', '', '', '', 'Best', '', 'Best', '', '', 'Worst', '', '', '', '', '', '', '', '', 'Best']

    marker = dict(symbol=symbols[:19], color=colors[:19], size=sizes[:19])
    self.plot_1.data = go.Scatter(x=x[:19], y=y[:19], marker=marker,text=markers_texts[:19])

   
    marker = dict(symbol=symbols[:20], color=colors[:20], size=sizes[:20])
    self.plot_2.data = go.Scatter(x=x[:20], y=y[:20], marker=marker,text=markers_texts[:20])

The app is here for you to see it in action:

https://anvil.works/build#clone:ZLGC2ZVGA236ZUOB=IZ43PLDDJREJQ7CAWKGOYOZF

I couldn’t find a reason.

Thanks

#2

This is built in to Plotly, their docs say:

If there are less than 20 points and the trace is not stacked then the default is “lines+markers”. Otherwise, “lines”.

(Here’s the part of their docs I’m talking about)

That sounds like a sensible default to me, they want to avoid a plot with 100s of points getting crowded out by markers.

You can override it by setting mode to 'lines+markers':

https://anvil.works/build#clone:7CJCGA6GLMZQEAKG=LCPAG2HH74HXY6PXVQ2VDB7C

44
Screen Shot 2019-08-22 at 16.27.44.png998×936 46.9 KB

Of course, if you wanted to switch to 'lines' when you had, say, 50 points, you could use a Python conditional for that:

mode='lines+markers' if len(y) < 50 else 'lines'
1 Like
#3

Thanks Shaun I missed that line in their docs.

1 Like