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Question

我在重载构造函数时遇到问题，它不会让我告诉它变量包含什么类型。我怎么能强迫一个类型，或者无论如何都要做这个工作......？

calc_readmit <- function(df) {
  if (nrow(df) == 1) return(NA)
  admitted <- c(0,cumsum(df$Index_admission))
  admitted <- admitted[-length(admitted)]
  dt1 <- df$dish_date[min(which(admitted > 0))-1]
  admit2 <- ifelse(admitted > 0, dt1, NA)
  time <- as.integer(df$adm_date) - admit2
  as.integer(ifelse(admitted > 0, time, NA))
}

library(data.table)
df <- data.table(df, key= "id")
df <- df[, time_to_readmission := calc_readmit(.SD), by= "id"]

R> df
      id Index_admission.   adm_date  dish_date time_to_readmission
 1: 1243             TRUE 2009-02-05 2009-02-08                  NA
 2: 1243             TRUE 2011-02-05 2011-02-19                 727
 3: 1244            FALSE 2009-02-07 2009-02-08                  NA
 4: 1244             TRUE 2009-03-05 2009-03-15                  NA
 5: 1244            FALSE 2011-04-05 2011-04-07                 751
 6: 1244            FALSE 2012-03-25 2012-03-27                1106
 7: 1244             TRUE 2012-05-05 2012-05-20                1147
 8: 1244             TRUE 2013-09-08 2013-09-15                1638
 9: 1244            FALSE 2014-01-05 2014-01-15                1757
10: 2333            FALSE 2010-01-01 2010-01-08                  NA
11: 2333            FALSE 2011-01-01 2011-01-05                  NA
12: 2333             TRUE 2011-02-02 2011-02-25                  NA
13: 2333            FALSE 2012-01-25 2012-01-28                 334
14: 5422             TRUE 2015-03-05 2015-03-15                  NA

Answer 1

我怎样才能强制使用某种类型，或者让它继续工作......

使用类型断言：

//  If first is Point all must be Points
let points = pointsOrWalls as Point[];

完成：

class Wall {w}
class Point {p}

class Foo {
    walls;
    name
    constructor(points: Point[], name?: string);
    constructor(walls: Wall[], name?: string);
    constructor(pointsOrWalls: (Wall | Point)[], name?: string) {
        if (pointsOrWalls[0] instanceof Point) {
            //  If first is Point all must be Points
            let points = pointsOrWalls as Point[];

            //  But here typescript says that pointsOrWalls is of type (Wall | Point)[]
            this.walls = points.map(function(point, ind, points) {
                return new Wall(point, points[++ind % points.length])
            })
        }else{
            //  Since these aren't points they are Walls
            this.walls = walls
        }
        this.name = name
    }   
}

在重载构造函数时键入问题

1 个答案:

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