こんな感じでとれます
import pandas as pd
import numpy as np
def argmaxdf(table):
argmax=lambda A: np.unravel_index(np.array(A).argmax(), np.array(A).shape)
row, col = argmax(table.values)
row, col = table.index[row], table.columns[col]
return row, col
table = pd.DataFrame(pd.DataFrame(np.random.rand(5,8),
index=list("abcde"),
columns=list("fghijklm")))
display(table,
argmaxdf(table)
)