tickmode="array" with custom tickvals ticktext doesn't work at all

[eromoe]

From plotly doc:

Example:

import pandas as pd
import numpy as np

np.random.seed(42)
feature = pd.DataFrame({'ds': pd.date_range('20200101', periods=100*24, freq='H'), 
                        'y': np.random.randint(0,20, 100*24) , 
                        'yhat': np.random.randint(0,20, 100*24) , 
                        'price': np.random.choice([6600, 7000, 5500, 7800], 100*24)})


import plotly.graph_objects as go
import plotly.offline as py
import plotly.express as px
from plotly.offline import init_notebook_mode

init_notebook_mode(connected=True)


y = feature.set_index('ds').resample('D')['y'].sum()

fig = go.Figure()
fig.add_trace(go.Scatter(x=y.index, y=y))


x_dates = y.index.to_series().dt.strftime('%Y-%m-%d').sort_values().unique()


layout = dict(
    xaxis=dict(
        tickmode="array",
        tickvals=np.arange(0, x_dates.shape[0],2).astype(int),
        ticktext=x_dates[::2],
        tickformat='%Y-%m-%d',
        tickangle=45,
    )
)

fig.update_layout(layout)
fig.show()

Result:

Since length of x_dates[::2] is 50 , the ticknumber doesn't match at all .
How do I sovle it ??

[nicolaskruchten]

Your layout = dict( ... line should start with fig.layout = dict( ... :)

[eromoe]

@nicolaskruchten Sorry , lost a line when editing , add fig.update_layout(layout) now .

You could try my code to verify the problem .

Only feed integer values to x and tickvals can get right xticks . I didn't tried this becasue similar code worked in matplotlib. So it looks like plotly has some problems when handling dtype { 'x' : date, tickvals: int } and dtype { 'x' : date, tickvals: date } .

[nicolaskruchten]

OK, so I'm not sure what the problem is here... what are you expecting to see that you're not seeing?

[nicolaskruchten]

Let's look at a simpler example with fewer moving parts which seems to work well enough... Is this as you're expecting?

import plotly.graph_objects as go

fig = go.Figure()
fig.add_trace(go.Scatter(x=["2010-01-01", "2010-02-01", "2010-03-01"], y=[1,3,2]))
fig.update_xaxes(tickvals=["2010-01-15", "2010-02-15"], ticktext=["A","B"])
fig.show()

[eromoe]

Similar, on my example . x is date type , tickvals is int and ticktext is string , working in matplotlib . I also tried
1 . x date , tickvals date ticktext string
2. x string, tickvals string , ticktext string

Neither work, so I post this issue .

[nicolaskruchten]

I'm really sorry but I'm having a lot of trouble understanding the issue you're describing when you say "neither work"... In the example I've posted above, x, tickvals and ticktext are all strings, so it's case 2 you describe above and the output is as I would expect it. The behaviour is the same if x and tickvals are dates.

If you could tell me what "doesn't work" about the display above I would gladly help you, but I'm not familiar enough with what matplotlib does to be able to infer this from what you've written :)

[eromoe]

OK, I put full example here :

I like to see

import pandas as pd
import numpy as np

np.random.seed(42)
feature = pd.DataFrame({'ds': pd.date_range('20200101', periods=100*24, freq='H'), 
                        'y': np.random.randint(0,20, 100*24) , 
                        'yhat': np.random.randint(0,20, 100*24) , 
                        'price': np.random.choice([6600, 7000, 5500, 7800], 100*24)})


import plotly.graph_objects as go
import plotly.offline as py
import plotly.express as px
from plotly.offline import init_notebook_mode

init_notebook_mode(connected=True)


y = feature.set_index('ds').resample('D')['y'].sum()

fig = go.Figure()

x_dates = y.index.to_series().dt.strftime('%Y-%m-%d').sort_values().unique()
fig.add_trace(go.Scatter(x=x_dates, y=y))

layout = dict(
    xaxis=dict(
        tickmode="auto",
        nticks=50,
        tickformat='%Y-%m-%d',
        tickangle=45,
    )
)

fig.update_layout(layout)
fig.show()

---

tickmode="auto" and nticks=50 is fine for me .

I am here just want to report this problem , because plotly is very handy now, I hope it would be bettter

1. x string, tickvals string , ticktext string , doesn't show 50 xticks :

import pandas as pd
import numpy as np

np.random.seed(42)
feature = pd.DataFrame({'ds': pd.date_range('20200101', periods=100*24, freq='H'), 
                        'y': np.random.randint(0,20, 100*24) , 
                        'yhat': np.random.randint(0,20, 100*24) , 
                        'price': np.random.choice([6600, 7000, 5500, 7800], 100*24)})


import plotly.graph_objects as go
import plotly.offline as py
import plotly.express as px
from plotly.offline import init_notebook_mode

init_notebook_mode(connected=True)


y = feature.set_index('ds').resample('D')['y'].sum()

fig = go.Figure()

x_dates = y.index.to_series().dt.strftime('%Y-%m-%d').sort_values().unique()
fig.add_trace(go.Scatter(x=x_dates, y=y))    # x is string

layout = dict(
    xaxis=dict(
        tickmode="array",
        tickvals=x_dates[::2],    # string
        ticktext=x_dates[::2],    # string 
        tickformat='%Y-%m-%d',
        tickangle=45,
    )
)

fig.update_layout(layout)
fig.show()

results with wrong xticks :

2 . x date , tickvals date ticktext string

import pandas as pd
import numpy as np

np.random.seed(42)
feature = pd.DataFrame({'ds': pd.date_range('20200101', periods=100*24, freq='H'), 
                        'y': np.random.randint(0,20, 100*24) , 
                        'yhat': np.random.randint(0,20, 100*24) , 
                        'price': np.random.choice([6600, 7000, 5500, 7800], 100*24)})


import plotly.graph_objects as go
import plotly.offline as py
import plotly.express as px
from plotly.offline import init_notebook_mode

init_notebook_mode(connected=True)


y = feature.set_index('ds').resample('D')['y'].sum()

fig = go.Figure()

x_dates = y.index.to_series().dt.strftime('%Y-%m-%d').sort_values().unique()
fig.add_trace(go.Scatter(x=y.index, y=y))   # x is date

layout = dict(
    xaxis=dict(
        tickmode="array",
        tickvals=y.index[::2],   #  date
        ticktext=x_dates[::2],    # string
        tickformat='%Y-%m-%d',
        tickangle=45,
    )
)

fig.update_layout(layout)
fig.show()

still wrong result

[nicolaskruchten]

Ah, OK, the problem is that you're not seeing as many tick labels as you would expect, got it.

There does seem to be a bug here, which I'll investigate, because while I get the expected output with:

import plotly.graph_objects as go

fig = go.Figure()
fig.add_trace(go.Scatter(x=["2010-01-01", "2010-02-01", "2010-03-01"], y=[1,3,2]))
fig.update_xaxes(tickvals=["2010-01-15", "2010-02-15"], ticktext=["A","B"])
fig.show()

If I then manually set tickmode="array" I see the default ticks, even though setting tickvals internally is meant to set tickmode="array" !

[gvwilson]

Hi - we are trying to tidy up the stale issues and PRs in Plotly's public repositories so that we can focus on things that are still important to our community. Since this one has been sitting for several years, I'm going to close it; if it is still a concern, please add a comment letting us know what recent version of our software you've checked it with so that I can reopen it and add it to our backlog. Thanks for your help - @gvwilson