具有多个条件的 Altair 分组条形图

Question

我有一个名为 table 的 DataFrame：

    TERM                        Bitcoin       S&P500    Real Estate Gold
0   High-Inflation/ Short term  3097.94       -3700.78  761.23      6512.71
1   High-Inflation/ Mid term    —             -3080.01  -8434.66    3242.40
2   High-Inflation/ Long term   —             -2089.25  -9117.96    8174.43
3   Low-Inflation/ Short term   780200.00     -273.71   1824.72     2214.51
4   Low-Inflation/ Mid term     21013600.00   5331.40   35810.58    -2879.37
5   Low-Inflation/ Long term    978017143.00. 15045.41  35895.81    861.90

我想制作一个分组（或堆叠）条形图，根据 TERM 列区分每个资产的 return 投资。我试过这个：

alt.Chart(table).transform_fold(
    ["Bitcoin", "S&P500", "Real Estate", "Gold"], as_=["key", "value"]
).mark_bar().encode(
        x="key:N",
        y="value:Q",
        color="key:N",
        column="TERM",
    )

但这不起作用。

Answer 1

它似乎工作正常，唯一的问题是这些值的比例差异很大，只有最大的才会出现在线性比例上。您可以通过切换到 symlog 比例来解决这个问题。例如：

import pandas as pd
import io
import altair as alt

table = pd.read_csv(io.StringIO("""\
row    TERM                        Bitcoin       S&P500   "Real Estate" Gold
0   "High-Inflation/ Short term"  3097.94       -3700.78  761.23      6512.71
1   "High-Inflation/ Mid term"    —             -3080.01  -8434.66    3242.40
2   "High-Inflation/ Long term"   —             -2089.25  -9117.96    8174.43
3   "Low-Inflation/ Short term"   780200.00     -273.71   1824.72     2214.51
4   "Low-Inflation/ Mid term"     21013600.00   5331.40   35810.58    -2879.37
5   "Low-Inflation/ Long term"    978017143.00. 15045.41  35895.81    861.90
"""), delim_whitespace=True)

alt.Chart(table).transform_fold(
    ["Bitcoin", "S&P500", "Real Estate", "Gold"], as_=["key", "value"]
).mark_bar().encode(
    x="key:N",
    y=alt.Y("value:Q", scale=alt.Scale(type='symlog')),
    color="key:N",
    column="TERM",
)

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