擅长:python、mysql、java
<p>温家宝的回答也很好。我有不同的解决方法。我会边走边解释:</p>
<pre><code># creates a dictionary of all the symbols and their max values
value_maps = dict(stocks_features.loc[stocks_features.\
groupby('Symbol').High.agg('idxmax')][['Symbol', 'High']].values)
# sets Max_Yearly_Price equal to the symbol
stocks_features['Max_Yearly_Price'] = stocks_features['Symbol']
# replaces the symbol wiht the corresponding value from the dicitonary
stocks_features['Max_Yearly_Price'] = stocks_features['Max_Yearly_Price'].map(value_maps)
# ouput
Date Symbol Open High Low Close Volume Daily Return Max_Yearly_Price
0 2016-01-04 AAPL 102.61 105.37 102.00 105.35 672811900.025703 NaN 105.85
1 2016-01-05 AAPL 105.75 105.85 102.41 102.71 557909920.019960 NaN 105.85
2 2016-12-28 AMZN 776.25 780.00 770.50 772.13 33010250.009122 NaN 780.00
3 2016-12-29 AMZN 772.40 773.40 760.85 765.15 31582990.020377 NaN 780.00
</code></pre>