熊猫根据另一列的重复值创建具有最大值的列

Question

大家好，我有这个数据框。我正在尝试创建 2 个附加列，max_temperature 和 min_temperature 来记录基于stayid 的最高和最低温度值。我该怎么做？

Answer 1

尝试 groupby、agg 和 pd.join

  newdf=(df.set_index('stayid')#Set stayid to allow joining of the aggregated to the main df
    .join(# This joins the ggregated df to main df
        df.groupby('stayid')['temp'].agg([min,max])# Compute the min and max temperature and put them into a summarised df
    ).rename(columns={'min':'min_temp', 'max':'max_temp'}))#rename the min and max columns)