:orphan:
:html_theme.sidebar_secondary.remove:
.. This document is auto-generated by the altair-gallery extension. Do not modify directly.
.. _gallery_scatter_with_loess:
Scatter Plot with LOESS Lines
-----------------------------
This example shows how to add a trend line to a scatter plot using
the LOESS transform (LOcally Estimated Scatter Plot Smoothing).
.. altair-plot::
:remove-code:
import altair as alt
import pandas as pd
import numpy as np
np.random.seed(1)
source = pd.DataFrame({
'x': np.arange(100),
'A': np.random.randn(100).cumsum(),
'B': np.random.randn(100).cumsum(),
'C': np.random.randn(100).cumsum(),
})
base = alt.Chart(source).mark_circle(opacity=0.5).transform_fold(
fold=['A', 'B', 'C'],
as_=['category', 'y']
).encode(
alt.X('x:Q'),
alt.Y('y:Q'),
alt.Color('category:N')
)
base + base.transform_loess('x', 'y', groupby=['category']).mark_line(size=4)
# No channel encoding options are specified in this chart
# so the code is the same as for the method-based syntax.
.. tab-set::
.. tab-item:: Method syntax
:sync: method
.. code:: python
import altair as alt
import pandas as pd
import numpy as np
np.random.seed(1)
source = pd.DataFrame({
'x': np.arange(100),
'A': np.random.randn(100).cumsum(),
'B': np.random.randn(100).cumsum(),
'C': np.random.randn(100).cumsum(),
})
base = alt.Chart(source).mark_circle(opacity=0.5).transform_fold(
fold=['A', 'B', 'C'],
as_=['category', 'y']
).encode(
alt.X('x:Q'),
alt.Y('y:Q'),
alt.Color('category:N')
)
base + base.transform_loess('x', 'y', groupby=['category']).mark_line(size=4)
.. tab-item:: Attribute syntax
:sync: attribute
.. code:: python
import altair as alt
import pandas as pd
import numpy as np
np.random.seed(1)
source = pd.DataFrame({
'x': np.arange(100),
'A': np.random.randn(100).cumsum(),
'B': np.random.randn(100).cumsum(),
'C': np.random.randn(100).cumsum(),
})
base = alt.Chart(source).mark_circle(opacity=0.5).transform_fold(
fold=['A', 'B', 'C'],
as_=['category', 'y']
).encode(
alt.X('x:Q'),
alt.Y('y:Q'),
alt.Color('category:N')
)
base + base.transform_loess('x', 'y', groupby=['category']).mark_line(size=4)
# No channel encoding options are specified in this chart
# so the code is the same as for the method-based syntax.