How to loop through through list of data frames to set column names in R?

Question

I have huge list of data frames and I want to set column names as per the the condition of the first column and fourth row. Please find my sample data below:

sample_data<-data.frame(a= c("\"\"","This","Week","1","2",  "3",   "4",  "5", "6" ),b=c("\"\""      , "Last"   ,   "Week"  , "(1)"    ,       "(2)"   ,       "(3)"     ,       "(4)"     ,           "(5)"   ,      "(6)"   ) ,c=c("\"\"" , "End","2008"  , "<1>",   "<2>",  "<3>", "<4>", "<5>", "<6>"  ) ,
                            d=c(""   ,    "Name"   ,   "" ,      "Tiger Woods" ,  "Sergio Garcia" ,"Phil Mickelson" ,"Padraig Harrington", "Vijay Singh" ,"Robert Karlsson") ,e=c("", "Country" ,  "",       "United States" ,"Spain",         "United States" , "Ireland" ,           "Fiji" , "Sweden"     ),
                            f=c("" ,  "Average" ,  "Points" ,"11.664"    ,    "7.992"    ,     "6.871"  ,        "6.832"   ,           "6.631"   ,    "5.017"  ),f=c("", "Total" ,"Points","466.573" ,"415.591" ,"336.674", "348.431",  "358.071", "265.906" ))



another_data<-data.frame(a=c("\"\"","Last", "Week" ,"\"\"","(50)", "(55)","(51)","(52)"),b=c("\"\"" ,"End", "2011","\"\"", "<148>","<70>","<49>","<51>"),c=c("","Name", "\"\"" ,"" ,"Kyle Stanley" , "Kevin Na" ,"Gonzalo Fdez-Castano" ,"Ryo Ishikawa") ,
                              d=c("","State","\"\"","\"\"", "United States","United States" ,"Spain" ,"Japan"),e=c("\"\"" ,"Country" ,"\"\"","\"\"","United States", "United States" ,"Spain","Japan"),f=c("\"\"","Average" ,"Points" ,"","2.694" ,"2.560","2.544" ,"2.539")) 
     
               
list_df<-list(sample_data,another_data)


list_df
[[1]]
     a    b    c                  d             e       f     f.1
1   ""   ""   ""                                                 
2 This Last  End               Name       Country Average   Total
3 Week Week 2008                                   Points  Points
4    1  (1)  <1>        Tiger Woods United States  11.664 466.573
5    2  (2)  <2>      Sergio Garcia         Spain   7.992 415.591
6    3  (3)  <3>     Phil Mickelson United States   6.871 336.674
7    4  (4)  <4> Padraig Harrington       Ireland   6.832 348.431
8    5  (5)  <5>        Vijay Singh          Fiji   6.631 358.071
9    6  (6)  <6>    Robert Karlsson        Sweden   5.017 265.906

[[2]]
     a     b                    c             d             e       f
1   ""    ""                                               ""      ""
2 Last   End                 Name         State       Country Average
3 Week  2011                   ""            ""            ""  Points
4   ""    ""                                 ""            ""        
5 (50) <148>         Kyle Stanley United States United States   2.694
6 (55)  <70>             Kevin Na United States United States   2.560
7 (51)  <49> Gonzalo Fdez-Castano         Spain         Spain   2.544
8 (52)  <51>         Ryo Ishikawa         Japan         Japan   2.539

So what i want to do is to check if the fourth row contains "" . If so, merge everything between the fourth row to first row of the data frame. On the other hand, if the fourth row does not contain "" , then merge everything between third row to first row of the data frame.

Here is my trial:

for (index in 1:length(list_df))
{

  if(list_df[[index]][4,1]=="")
    {
      list_df[[index]]<-setNames(as.data.frame(list_df[[index]][-(1:4), ]),
                                                sapply(as.data.frame(list_df[[index]][1:4, ]), paste, collapse = ""))
    }
  else if(list_df[[index]][4,1]!="")
  {
    list_df[[index]]<-setNames(as.data.frame(list_df[[index]][-(1:3), ]),
                                sapply(as.data.frame(list_df[[index]][1:3, ]), paste, collapse = ""))
  }
  {
    return(list_df)
  }

}

But this is not giving me the desired output. Working for the first condition only but not considering the second condition.

Here is the output I am getting:

list_df

   [[1]]
      ThisWeek LastWeek End2008               Name       Country AveragePoints TotalPoints
    4        1      (1)     <1>        Tiger Woods United States        11.664     466.573
    5        2      (2)     <2>      Sergio Garcia         Spain         7.992     415.591
    6        3      (3)     <3>     Phil Mickelson United States         6.871     336.674
    7        4      (4)     <4> Padraig Harrington       Ireland         6.832     348.431
    8        5      (5)     <5>        Vijay Singh          Fiji         6.631     358.071
    9        6      (6)     <6>    Robert Karlsson        Sweden         5.017     265.906
    
    [[2]]
         a     b                    c             d             e       f
    1                                                                    
    2 Last   End                 Name       Country       Country Average
    3 Week  2011                                                   Points
    4                                                                    
    5 (50) <148>         Kyle Stanley United States United States   2.694
    6 (55)  <70>             Kevin Na United States United States   2.560
    7 (51)  <49> Gonzalo Fdez-Castano         Spain         Spain   2.544
    8 (52)  <51>         Ryo Ishikawa         Japan         Japan   2.539

However, the desired output is as follows:

list_df

[[1]]
          ThisWeek LastWeek End2008               Name       Country AveragePoints TotalPoints
        4        1      (1)     <1>        Tiger Woods United States        11.664     466.573
        5        2      (2)     <2>      Sergio Garcia         Spain         7.992     415.591
        6        3      (3)     <3>     Phil Mickelson United States         6.871     336.674
        7        4      (4)     <4> Padraig Harrington       Ireland         6.832     348.431
        8        5      (5)     <5>        Vijay Singh          Fiji         6.631     358.071
        9        6      (6)     <6>    Robert Karlsson        Sweden         5.017     265.906

[[2]]
   LastWeek   End2011         Name                  State        Country  AveragePoints
5    (50)     <148>         Kyle Stanley           United States United States   2.694
6    (55)      <70>         Kevin Na               United States United States   2.560
7    (51)      <49>         Gonzalo Fdez-Castano   Spain         Spain           2.544
8    (52)      <51>         Ryo Ishikawa           Japan         Japan           2.539

I am so perplexed by this. I don't know why one of the conditions are being neglected. Can anyone help me with this please?

Answer 1

Usually it is easy to iterate over the list with lapply . You can try :

lapply(list_df, function(x) {
  if (x[4, 1] == '""') {
    names(x) = gsub('"', '', trimws(sapply(x[1:4, ], paste, collapse = "")))
    x[-c(1:4), ]
  }
  else {
    names(x) = gsub('"', '', trimws(sapply(x[1:3, ], paste, collapse = "")))
    x[-c(1:3), ]
  }
})

#[[1]]
#  ThisWeek LastWeek End2008               Name       Country AveragePoints TotalPoints
#4        1      (1)     <1>        Tiger Woods United States        11.664     466.573
#5        2      (2)     <2>      Sergio Garcia         Spain         7.992     415.591
#6        3      (3)     <3>     Phil Mickelson United States         6.871     336.674
#7        4      (4)     <4> Padraig Harrington       Ireland         6.832     348.431
#8        5      (5)     <5>        Vijay Singh          Fiji         6.631     358.071
#9        6      (6)     <6>    Robert Karlsson        Sweden         5.017     265.906

#[[2]]
#  LastWeek End2011                 Name         State       Country AveragePoints
#5     (50)   <148>         Kyle Stanley United States United States         2.694
#6     (55)    <70>             Kevin Na United States United States         2.560
#7     (51)    <49> Gonzalo Fdez-Castano         Spain         Spain         2.544
#8     (52)    <51>         Ryo Ishikawa         Japan         Japan         2.539

---

As far as your for loop is concerned the main reason why it is not working is because you are looking for wrong character. The value at [4, 1] is "" and not empty string (Check another_data[4, 1] == '' vs another_data[4, 1] == '""' ). If you change that you should get the desired output. However, I did some additional changes in your for loop.

• Removed the additional else if condition as it is not needed.
• Added gsub as in my answer to remove quotes from column names
• return(list_df) doesn't make sense since we are already changing the list_df in for loop so removed it.

for (index in 1:length(list_df)) {
  if(list_df[[index]][4,1] == '""') {
    list_df[[index]]<-setNames(as.data.frame(list_df[[index]][-(1:4), ]),
                    gsub('"', '',sapply(as.data.frame(list_df[[index]][1:4, ]), 
                 paste, collapse = "")))
  }
  else{
    list_df[[index]]<-setNames(as.data.frame(list_df[[index]][-(1:3), ]),
                  gsub('"', '', sapply(as.data.frame(list_df[[index]][1:3, ]), 
                  paste, collapse = "")))
  }
}