python - 获取第二个系列中第一个系列中元素的索引

Question

我想为 larger 系列获取 smaller 系列中所有值的索引。答案在下面存储在 ans 变量中的代码片段中。

import pandas as pd

smaller = pd.Series(["a","g","b","k"])
larger = pd.Series(["a","b","c","d","e","f","g","h","i","j","k","l","m"])

# ans to be generated by some unknown combination of functions
ans = [0,6,1,10]
print(larger.iloc[ans,])
print(smaller)
assert(smaller.tolist() == larger.iloc[ans,].tolist())

上下文:系列 larger 用作 numpy 矩阵中列的索引，系列 smaller 用作 numpy 向量中列的索引。我需要矩阵和向量的索引来匹配。

Answer 1

你可以反转你的 larger 系列，然后用 smaller 索引它:

larger_rev = pd.Series(larger.index, larger.values)
res = larger_rev[smaller].values

print(res)

array([ 0,  6,  1, 10], dtype=int64)