Plotting line chart in local time zone

Suraj_Bhanu_Jat · May 27, 2024, 10:54pm

streamlit/streamlit/blob/84e4cb390e004da1441f3e5665b2405ecadac8a6/lib/streamlit/elements/arrow_altair.py#L1186-L1197


      
          def _get_scale(df: pd.DataFrame, column_name: Optional[str]) -> alt.Scale:
              import altair as alt
          
              # Set the X and Y axes' scale to "utc" if they contain date values.
              # This causes time data to be displayed in UTC, rather the user's local
              # time zone. (By default, vega-lite displays time data in the browser's
              # local time zone, regardless of which time zone the data specifies:
              # https://vega.github.io/vega-lite/docs/timeunit.html#output).
              if _is_date_column(df, column_name):
                  return alt.Scale(type="utc")
          
              return alt.Scale()

Hello, is the issue resolved?

My dataframe is in local timezone but when I plot the data using st.linechart(). Data is plotted automatically in the UTC timezone even though I have converted the data to local time zone.

Is the problem in my code or streamlit only plots using the UTC timezone automatically irrespective of the timezone info in dataframe.

Thanks in advance!
Suraj Jat

tonykip · May 28, 2024, 8:48pm

Hi @Suraj_Bhanu_Jat,

Thanks for sharing this question!

Streamlit, by default, uses Vega Lite for plotting which displays time data in UTC regardless if timezone info in dataframe.

In your case, since you are using st.line_chart, Streamlit’s default behavior is to plot the data in UTC if it detects date values. You have a couple of options to resolve this. One is by manually adjusting the timezone within your data so that Vega Lite won’t interpret it as a date value and convert it to UTC.

Please share your code if this does not help resolve the issue.

Suraj_Bhanu_Jat · May 28, 2024, 9:24pm

Hello,

Thanks for your revert.

I am getting the data in UTC format from data source, But I want to plot it in UTC-4 time zone

I have manually changed the data frame to UTC-4 time zone. But when I am plotting the same converted data frame, it is getting plotted in UTC time zone.

Goyo · May 28, 2024, 9:54pm

You have to remove the tz information after the conversion.

Suraj_Bhanu_Jat · May 29, 2024, 7:44am

So basically I am fetching data from an API, and I am getting the data in UTC format from API.

So this is the function to fetch the data.

I want to give the start and end date in the function. Below is the code for date selection.

Here I want to select the date such that start date is automatically in UTC-4 format. For example if I want data from midnight i should be able to select the date such that it gives me the data on the basis of local time zone but not UTC.

Suraj_Bhanu_Jat · May 30, 2024, 10:24am

Thanks for your suggestion:)

Suraj_Bhanu_Jat · June 1, 2024, 10:02pm

Can someone please help me with the query?

Sai_SaiGraph · June 2, 2024, 3:32am

Suraj
On a side note what extension u use to display the lines for indentation.
Thanks
Sai

Suraj_Bhanu_Jat · June 2, 2024, 9:23am

Sorry, I am a newbie in coding. are you asking for a code editor? I am using visualstudio.

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Plotting line chart in local time zone

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