Question

我有一个行名相同的数据集。例如，我想在数据（第0,1,2,3,4行）中使用与A的最后一行（第4行）相同的价格。所以所有的As都等于60.但是我希望这对我的整个数据都是如此。 B和C等的计算相同。我有很多数据。是不是可以在熊猫中做到这一点？我不想将它们分组，我想保留所有As等。数据集的一个例子如下。

   Brand      Price    Color      Category

0   A       10         Blue       Shoes
1   A       20         Red        Shoes
2   A       30         Yellow     Shoes 
3   A       40         Pink       Shoes 
4   A       60         Purple     Shoes  
5   B       100        Red        Shoes
6   B       130        Green      Shoes
7   B       150        Blue       Shoes
8   C       170        Yellow     Shoes
9   C       20         Green      Shoes

谢谢

Answer 1

使用map创建的Series keep='last'与mapping = df.drop_duplicates('Brand', keep='last').set_index('Brand')['Price'] df['Price'] = df['Brand'].map(mapping) print (df) Brand Price Color Category 0 A 60 Blue Shoes 1 A 60 Red Shoes 2 A 60 Yellow Shoes 3 A 60 Pink Shoes 4 A 60 Purple Shoes 5 B 150 Red Shoes 6 B 150 Green Shoes 7 B 150 Blue Shoes 8 C 20 Yellow Shoes 9 C 20 Green Shoes一起使用每组的最新值：

Brand

如果需要按多列定义分组（例如Category和df['Price'] = df.groupby(['Brand', 'Category'])['Price'].transform('last') print (df) Brand Price Color Category 0 A 60 Blue Shoes 1 A 60 Red Shoes 2 A 60 Yellow Shoes 3 A 60 Pink Shoes 4 A 60 Purple Shoes 5 B 150 Red Shoes 6 B 150 Green Shoes 7 B 150 Blue Shoes 8 C 20 Yellow Shoes 9 C 20 Green Shoes），可以drop_duplicates使用transform：

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo  {
    application.applicationIconBadgeNumber = 0;            

    if (application.applicationState == UIApplicationStateActive) {                
        // Nothing to do if applicationState is Inactive, the iOS already displayed an alert view.                
        UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Did receive a Remote Notification" message:[NSString stringWithFormat:@"Your App name received this notification while it was running:\n%@",[[userInfo objectForKey:@"aps"] objectForKey:@"alert"]]delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [alertView show];          
    }    
}

在Pandas中为相同的命名行应用相同名称行的最后一个条目

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