Question

我有以下数据集：

clubs <- c("AZ","AZ","AZ","AZ")
won <- c("W","L","W","L")
last_match <- c("NA", "NA", "NA","NA")

df_new <- data.frame(clubs, won, last_match)

我现在想做的是：

在csv中读到
获取行的第二个到结尾
查看最后一场比赛是否胜出

以下代码可以正常使用：

calc <- function(){

  setwd("...")
  df_new <- read.csv2("df_club.csv", header = T)

  #checking
  print(head(df_new))

  for(i in 2:nrow(df_new)){

   df_new$last_match[i] <-  df_new$won[i-1]
  }

  #checking
  print(head(df_new))

}

出于概述目的，我想将计算部分放在不同的函数中。这就是我尝试这个的原因：

 #define calculating formule
 calculate_last_win <- function(df){

  for(i in 2:nrow(df_new)){

   df_new$last_match[i] <-  df_new$won[i-1]
  }
  return(df)
 }


#normal function

calc <- function(){

  setwd("...")
  df_new <- read.csv2("df_club.csv", header = T)

  #checking
  print(head(df_new))

  calculate_last_win(df_new)

  #checking
  print(head(df_new))

 }

但是我的输出没有变化。对于出了什么问题的任何想法？

Answer 1

在calc中，将行calculate_last_win(df_new)替换为df_new <- calculate_last_win(df_new)，在函数calculate_last_win中，将df_new替换为df。

clubs <- c("AZ","AZ","AZ","AZ")
won <- c("W","L","W","L")

dfNew <-data.frame(clubs, won)


#define calculating formule
calculate_last_win <- function(df){

  for(i in 2:nrow(df)){

    df[i,"last_match"] <-  df[i-1,"won"]
  }
  return(df)
}


#normal function

calc <- function(){

  setwd("...")
  df_new <- dfNew

  #checking
  print(head(df_new))

  df_new <- calculate_last_win(df_new)

  #checking
  print(head(df_new))

  return ( df_new )
}

> calc()
  clubs won
1    AZ   W
2    AZ   L
3    AZ   W
4    AZ   L
  clubs won last_match
1    AZ   W       <NA>
2    AZ   L          W
3    AZ   W          L
4    AZ   L          W
  clubs won last_match
1    AZ   W       <NA>
2    AZ   L          W
3    AZ   W          L
4    AZ   L          W

Answer 2

我认为你的功能应该是这样的。该函数需要df_new为df。

calculate_last_win <- function(df){

  for(i in 2:nrow(df)){

   df$last_match[i] <-  df$won[i-1]
  }
  return(df)
 }

在调用函数后，我还会检查return(df)是否正在替换df_new。

在函数内调用函数似乎不起作用

2 个答案: