Question

我正在尝试根据数据帧中另一列的特定值向列添加增量值。这样...

import UIKit
import SDWebImage

class testGraphic2ViewController: UIViewController, SDWebImageManagerDelegate {
    @IBOutlet weak var imageView: UIImageView!

    let postImageUrlStr = "https://firebasestorage.googleapis.com/v0/b/instagramclone-be6eb.appspot.com/o/posts%2FFBAE2BE9-F429-4D39-978C-DD2E24BF062D?alt=media&token=7b41569b-5451-4728-942c-6d43ec50350c"

    override func viewDidLoad() {
        super.viewDidLoad()
        SDWebImageManager.shared().delegate = self
        SDWebImageManager.shared().loadImage(with: URL(string: postImageUrlStr), options: [], progress: nil) { (image, data, error, cacheType, finished, url) in
            self.imageView.image = image
        }
    }

    func imageManager(_ imageManager: SDWebImageManager, transformDownloadedImage image: UIImage?, with imageURL: URL?) -> UIImage? {
        print("imageManager is called!")
        guard let image = image, let imageURL = imageURL else {
            return nil
        }
        if (imageURL.lastPathComponent == "large" && (image.size.width > 1000 || image.size.width > 1000)) {
            let targetSize = CGSize(width: 1000, height: 1000)
            UIGraphicsBeginImageContextWithOptions(targetSize, false, image.scale)
            image.draw(in: CGRect(origin: .zero, size: targetSize))

            let scaledImage = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()
            return scaledImage
        } else {
            return image
        }
    }

会变成这样：

col A   col B
 A        0
 B        1
 C        2
 A        3
 A        4
 B        5

曾尝试使用groupby函数，但无法真正了解设置B列的增量值。

有什么想法吗？

谢谢

Answer 1

我认为需要factorize：

df['col B'] = pd.factorize(df['col A'])[0] + 1
print (df)
  col A  col B
0     A      1
1     B      2
2     C      3
3     A      1
4     A      1
5     B      2

另一种解决方案：

df['col B'] = pd.Categorical(df['col A']).codes + 1
print (df)
  col A  col B
0     A      1
1     B      2
2     C      3
3     A      1
4     A      1
5     B      2

根据列的唯一值分配增量值

1 个答案: