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Px.histogram having X-axis sorting issue


I’m experimenting some troubles with my X-axis on my px.histogram.

I’m using Python 3.6.3 and Plotly 4.8.0 .

Data are stored in a pd.DataFrame object. It has 2 columns :

  • time_shift (datetime) : 15 min range
  • cluster (int) : output from a clustering algorithm

Dataframe is sorted on “time_shift” column.


When i try to plot a histogram counting cluster for each time shift, i’m experimenting some issue.

        fig = px.histogram(live_data,

My X axis is not sorted, however my dataframe is. I can’t figure why ?

Thanks in advance for your help

Hi @Pepef welcome to the forum! Probably your time_shift axis is of string or object type and therefore it is considered as a categorical axis by plotly. You can change the format to datatime and see if the axis is sorted as expected.

1 Like

Thx for your answer :slight_smile: @Emmanuelle !

You are right my time_shift axis is an object.

As you suggested I change format to date.

fig = px.histogram(live_data,
        fig.update_layout(xaxis = dict(type = 'date'))

However it didn’t fix anything.

My object is actually a datetime.time and not a datetime.datetime.

I can trick it by adding a fake date to be a datetime.datetime and only displaying hours and minutes.

       fig = px.histogram(live_data,
        fig.update_layout(xaxis = dict(tickformat = '%H:%M',
                                               type = 'date'),
                          bargroupgap = 0.2)

It produces this :

It’s much better however it’s not following my time range of 15 minutes per bar. (now each bar represents 1 hour)

Do you have any idea on which parameters i can set to format my axis ?