Question

我今天开始与Altair一起玩，对选择有疑问。我创建了3个不同颜色的条形图，如下所示。现在，每当我单击一个条形图时，我都希望在其他两个条形图中突出显示该条形图。如果我不使用任何颜色，并且默认为蓝色，则效果很好，但是我不知道如何将颜色保留在选择中，而不是对所有三个图表使用相同的颜色。

df = pd.DataFrame({"Name":["Bulbasaur", "Charizard", "Mewtwo"], 
                  "HP":[45, 80, 100], 
                  "Attack":[30, 50, 60], 
                  "Defense":[40, 38, 42], 
                  "Type":["Grass", "Fire", "Psychic"]}) 


selection = alt.selection_single(fields=["Type 1"])

# This doesn't do much as I don't have a column named #73a1eb. But it's the colour code I'd like to use.
color1 = alt.condition(selection,
                  alt.Color("#73a1eb:N", legend=None), 
                  alt.value('lightgray'))

color2 = alt.condition(selection,
                  alt.Color("#73b9c7:N", legend=None),
                  alt.value('lightgray'))

color3 = alt.condition(selection,
                  alt.Color("#d7abf5:N", legend=None),
                  alt.value('lightgray'))

# The mark bar colour is overriden by color in encode

chart1 = alt.Chart(df, title="Average HP by Type")
            .mark_bar(color="#73a1eb", size = 12)
            .encode(x = 'mean(HP):Q',
                    y = alt.Y('Type 1:N', sort='-x'), 
                    tooltip=["Type 1", "mean(HP):Q"], 
                    color=color1)
            .properties(height=320,
                        width=300)
            .add_selection(selection)

chart2 = alt.Chart(df, title="Average Attack by Type")
            .mark_bar(color="#73a1eb", size = 12)
            .encode(x = 'mean(Attack):Q',
                    y = alt.Y('Type 1:N', sort='-x'), 
                    tooltip=["Type 1", "mean(HP):Q"], 
                    color=color1)
            .properties(height=320,
                        width=300)
            .add_selection(selection)

chart2 = alt.Chart(df, title="Average Defense by Type")
            .mark_bar(color="#73a1eb", size = 12)
            .encode(x = 'mean(Defense):Q',
                    y = alt.Y('Type 1:N', sort='-x'), 
                    tooltip=["Type 1", "mean(HP):Q"], 
                    color=color1)
            .properties(height=320,
                        width=300)
            .add_selection(selection)

alt.hconcat(chart1, chart2, chart3).configure_axis(grid=False).configure_axisBottom().resolve_scale(x = 'shared')

Answer 1

在编写alt.Color("#73a1eb:N")时，这意味着您希望根据名为"#73a1eb"的具有名义（"N"）类型的列对颜色进行编码。

似乎您要指定颜色值而不是颜色编码，在这种情况下，您可以编写alt.value("#73a1eb")。因此您的情况将如下所示：

color1 = alt.condition(selection,
                       alt.value("#73a1eb"),
                       alt.value('lightgray'))

选择不同颜色的Altair

1 个答案: