Get y-value of a datasource given a x-value (in floats)

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1

Hello all

I managed to write a plot where I can dynamically set a span.

Know I would like to find the y-value of the intersection of the datasource with my span.

Or with other words:
Given a x-value, how can I find the corresponding y-value (as in the figure) of a datasource?

So far I didn’t find find a solution, or I did not know what to look for…

Thanks in advance.

2

Is your data source a ColumnDataSource? What does it look like?

···

On Wednesday, September 7, 2016 at 8:45:55 AM UTC-4, [email protected] wrote:

Hello all

I managed to write a plot where I can dynamically set a span.

Know I would like to find the y-value of the intersection of the datasource with my span.

Or with other words:

613×594 22.2 KB

Given a x-value, how can I find the corresponding y-value (as in the figure) of a datasource?

So far I didn’t find find a solution, or I did not know what to look for…

Thanks in advance.

3

The source is indeed a ColumnDataSource. The source data in the image is just from one of the examples in the docs.
But in my application I also use ColumnDataSources. The red line is a span.

But I know the x location value of the span in my JavaScript Callback.

···

On Wednesday, 7 September 2016 17:38:52 UTC+2, Reuben Jacobs wrote:

Is your data source a ColumnDataSource? What does it look like?

On Wednesday, September 7, 2016 at 8:45:55 AM UTC-4, [email protected] wrote:

Hello all

I managed to write a plot where I can dynamically set a span.

Know I would like to find the y-value of the intersection of the datasource with my span.

Or with other words:

613×594 22.2 KB

Given a x-value, how can I find the corresponding y-value (as in the figure) of a datasource?

So far I didn’t find find a solution, or I did not know what to look for…

Thanks in advance.

4

Bokeh just does graphics; this is something you should do using another library. This procedure is called “interpolation.”

For example

import numpy as np

x = source.data[‘x’]

y = source.data[‘y’]

interp = np.interp1d(y, x)

some_x = interp(some_y)

···

On Wednesday, September 7, 2016 at 8:45:55 AM UTC-4, [email protected] wrote:

Hello all

I managed to write a plot where I can dynamically set a span.

Know I would like to find the y-value of the intersection of the datasource with my span.

Or with other words:

613×594 22.2 KB

Given a x-value, how can I find the corresponding y-value (as in the figure) of a datasource?

So far I didn’t find find a solution, or I did not know what to look for…

Thanks in advance.

5

Sorry that function is in scipy; the import should be from scipy.interpolate import interp1d. Maybe there is something similar in numpy but I used the scipy syntax in my example.

···

On Tuesday, September 20, 2016 at 8:26:07 PM UTC-4, Henry Harrison wrote:

Bokeh just does graphics; this is something you should do using another library. This procedure is called “interpolation.”

For example

import numpy as np

x = source.data[‘x’]

y = source.data[‘y’]

interp = np.interp1d(y, x)

some_x = interp(some_y)

On Wednesday, September 7, 2016 at 8:45:55 AM UTC-4, [email protected] wrote:

Hello all

I managed to write a plot where I can dynamically set a span.

Know I would like to find the y-value of the intersection of the datasource with my span.

Or with other words:

613×594 22.2 KB

Given a x-value, how can I find the corresponding y-value (as in the figure) of a datasource?

So far I didn’t find find a solution, or I did not know what to look for…

Thanks in advance.