Question

如何转换如下列表：

data_list = [0,1,2,3,4,5,6,7,8,9]

到一个数组（我正在使用numpy），看起来像：

data_array = [ [0,1] , [2,3] , [4,5] , [6,7] , [8,9] ]

我可以从列表的开头切片并将它们附加到空数组吗？

由于

Answer 1

>>> import numpy as np
>>> np.array(data_list).reshape(-1, 2)
array([[0, 1],
       [2, 3],
       [4, 5],
       [6, 7],
       [8, 9]])

（reshape方法在数组上返回一个新的“视图”;它不会复制数据。）

Answer 2

Car

针对：

import Foundation

extension UITabBarController {
    
    private struct AssociatedKeys {
        // Declare a global var to produce a unique address as the assoc object handle
        static var orgConstraintConstant: UInt8 = 0
        static var orgTabBarAlpha       : UInt8 = 1
    }
    
    var orgConstraintConstant: CGFloat? {
        get { return objc_getAssociatedObject(self, &AssociatedKeys.orgConstraintConstant) as? CGFloat }
        set { objc_setAssociatedObject(self, &AssociatedKeys.orgConstraintConstant, newValue, .OBJC_ASSOCIATION_COPY) }
    }
    
    var orgTabBarAlpha: CGFloat? {
        get { return objc_getAssociatedObject(self, &AssociatedKeys.orgTabBarAlpha) as? CGFloat }
        set { objc_setAssociatedObject(self, &AssociatedKeys.orgTabBarAlpha, newValue, .OBJC_ASSOCIATION_COPY) }
    }
    
    func setTabBarVisible(visible:Bool, animated:Bool, bottomConstraint: NSLayoutConstraint) {
        // bail if the current state matches the desired state
        if (tabBarIsVisible() == visible) { return }
        //define segment animation duration (note we have two segments so total animation time = times 2x)
        let segmentAnimationDuration = animated ? 0.15 : 0.0
        //we should show it
        if visible {
            //animate moving up
            UIView.animate(withDuration:  segmentAnimationDuration,
                           delay: 0,
                           options: [],
                           animations: {
                            [weak self] in
                            guard let self = self else { return }
                            bottomConstraint.constant = self.orgConstraintConstant ?? 0
                            self.view.layoutIfNeeded()
                           },
                           completion: {
                            (_) in
                            //animate tabbar fade in
                            UIView.animate(withDuration: segmentAnimationDuration) {
                                [weak self] in
                                guard let self = self else { return }
                                self.tabBar.alpha = self.orgTabBarAlpha ?? 0
                                self.view.layoutIfNeeded()
                            }
                           })
            //reset our values
            self.orgConstraintConstant = nil
        }
        //we should hide it
        else {
            //save our previous values
            self.orgConstraintConstant = bottomConstraint.constant
            self.orgTabBarAlpha = tabBar.alpha
            //animate fade bar out
            UIView.animate(withDuration:  segmentAnimationDuration,
                           delay: 0,
                           options: [],
                           animations: {
                            [weak self] in
                            guard let self = self else { return }
                            self.tabBar.alpha = 0.0
                            self.view.layoutIfNeeded()
                           },
                           completion: {
                            (_) in
                            //then animate moving down
                            UIView.animate(withDuration: segmentAnimationDuration) {
                                [weak self] in
                                guard let self = self else { return }
                                bottomConstraint.constant = bottomConstraint.constant - self.tabBar.frame.height + 4 // + 4 looks nicer on no-home button devices
                                //self.tabBar.alpha = 0.0
                                self.view.layoutIfNeeded()
                            }
                           })
        }
    }
    
    func tabBarIsVisible() ->Bool {
        return orgConstraintConstant == nil
    }
}

输出：

def nest_list(list1,rows, columns):    
        result=[]               
        start = 0
        end = columns
        for i in range(rows): 
            result.append(list1[start:end])
            start +=columns
            end += columns
        return result

如何在python中将平面列表转换为2D数组？

2 个答案: