To concatenate charts horizontally we can use the | operator: chart_1 | chart_2.
For vertical concatenation the operator & can be used: chart_1 & chart_2.
Below, we are combining four charts to create a 2x2 visualisation using (chart_1 | chart_2) & (chart_3 | chart_4).
To specify a title in each plot, we use title = 'The Title' inside $properties().
chart_disasters_1 = alt$Chart("https://raw.githubusercontent.com/vega/vega-datasets/master/data/disasters.csv")$
mark_line()$
encode(
x = 'Year:O',
y = 'Deaths:Q',
tooltip = 'Deaths:Q'
)$
transform_filter(
alt$FieldEqualPredicate(field = "Entity", equal = "Landslide")
)$
properties(
width = 400,
height = 200,
title = 'Landslide'
)$
interactive()
chart_disasters_2 = alt$Chart("https://raw.githubusercontent.com/vega/vega-datasets/master/data/disasters.csv")$
mark_line()$
encode(
x = 'Year:O',
y = 'Deaths:Q',
tooltip = 'Deaths:Q'
)$
transform_filter(
alt$FieldEqualPredicate(field = "Entity", equal = "Volcanic activity")
)$
properties(
width = 400,
height = 200,
title = 'Volcanic activity'
)$
interactive()
chart_disasters_3 = alt$Chart("https://raw.githubusercontent.com/vega/vega-datasets/master/data/disasters.csv")$
mark_line()$
encode(
x = 'Year:O',
y = 'Deaths:Q',
tooltip = 'Deaths:Q'
)$
transform_filter(
alt$FieldEqualPredicate(field = "Entity", equal = "Wildfire")
)$
properties(
width = 400,
height = 200,
title = 'Wildfire'
)$
interactive()
chart_disasters_4 = alt$Chart("https://raw.githubusercontent.com/vega/vega-datasets/master/data/disasters.csv")$
mark_line()$
encode(
x = 'Year:O',
y = 'Deaths:Q',
tooltip = 'Deaths:Q'
)$
transform_filter(
alt$FieldEqualPredicate(field = "Entity", equal = "Mass movement (dry)")
)$
properties(
width = 400,
height = 200,
title = 'Mass movement (dry)'
)$
interactive()
chart_combined = (chart_disasters_1 | chart_disasters_2) & (chart_disasters_3 | chart_disasters_4)