Support concatenation

[binste]

See #31 (comment)

[mattijn]

The comment in OP refers to two tile_charts next to each other.

Another concatenation issue is the following, while trying to add a basemap to the following example in the altair gallery: https://altair-viz.github.io/gallery/interval_selection_map_quakes.html

This works:

import altair as alt
import altair_tiles as til
from vega_datasets import data
import geopandas as gpd

# load data
gdf_quakies = gpd.read_file(data.earthquakes.url, driver="GeoJSON")

# defintion for interactive brush
brush = alt.selection_interval(
    encodings=["longitude"],
    empty=False,
    value={"longitude": [-50, -110]}
)

# world disk
sphere = alt.Chart(alt.sphere()).mark_geoshape(
    fill="transparent", stroke="lightgray", strokeWidth=1
)

# earthquakes as dots on map
quakes = alt.Chart(gdf_quakies).transform_calculate(
    lon="datum.geometry.coordinates[0]",
    lat="datum.geometry.coordinates[1]",
).mark_circle(opacity=0.35, tooltip=True).encode(
    longitude="lon:Q",
    latitude="lat:Q",
    color=alt.condition(brush, alt.value("goldenrod"), alt.value("steelblue")),
    size=alt.Size("mag:Q").scale(type="pow", range=[1, 1000], domain=[0, 7], exponent=4),
).add_params(brush)

# combine layers for the map
left_map = alt.layer(til.create_tiles_chart(), sphere, quakes).project(type="mercator").properties(width=300, height=300)
left_map

But adding bars as chart next to it, make the tile-layer disappear:

# histogram of binned earthquakes
bars = alt.Chart(gdf_quakies).mark_bar().encode(
    x=alt.X("mag:Q").bin(extent=[0,7]),
    y="count(mag):Q",
    color=alt.value("steelblue")
)

# filtered earthquakes
bars_overlay = bars.encode(color=alt.value("goldenrod")).transform_filter(brush)

# combine layers for histogram
right_bars = alt.layer(bars, bars_overlay)

left_map | right_bars

Increasing the width of the left_map does something:

left_map.properties(width=400) | right_bars

[tillnagel]

Same here. Just commenting to say this does not work independent on creation mode: when creating an independent map (through create_tiles_chart), and when adding a map to a chart (through add_tiles).

I also noticed that the tiles are not even requested. Meaning, the behavior is not: map is being rendered and then not displayed - but, I assume, the size of the map is wrongly specified due to the concatenation / some offset not being considered.