Question

嗨，我有一个像下面这样的pandas Dataframe 列是['music_id'，'users_id'，'得分']

@interface NSString (SHA2HEX)

/*
 Get the SHA2 (256 bit) digest as a hex string.
 */
@property (nonatomic, readonly) NSString* sha2hex;
@end

@implementation NSString (SHA2HEX)

- (NSString*)sha2hex
{
    NSData *data = [self dataUsingEncoding:NSUTF8StringEncoding];

    if (data.length > UINT32_MAX)
        return nil;

    uint8_t digest[CC_SHA256_DIGEST_LENGTH];
    CC_SHA256(data.bytes, (CC_LONG)data.length, digest);

    const int hexlen = CC_SHA256_DIGEST_LENGTH * 2;
    NSMutableString *hexstr = [NSMutableString stringWithCapacity:hexlen];

    for (int i = 0; i < CC_SHA256_DIGEST_LENGTH; i++) {
        [hexstr appendFormat:@"%02x", digest[i]];
    }

    return hexstr;
}

@end

我尝试制作一个像这样的新数据框：

A       a       1
A       c       2
A       b       1
B       e       2
B       a       3
B       b       1

pandas中有没有像这样的方法？谢谢！

Answer 1

使用set_index和unstack：

df.set_index([0,1])[2].unstack()

输出：

1    a    b    c    e
0                    
A  1.0  1.0  2.0  NaN
B  3.0  1.0  NaN  2.0

摆脱轴名称输出：

df.set_index([0,1])[2].unstack().rename_axis(None, axis=1).rename_axis(None)

     a    b    c    e
A  1.0  1.0  2.0  NaN
B  3.0  1.0  NaN  2.0

其中，df：

python / pandas传输数据集

1 个答案: