I have a big dataset df (354903 rows) with two columns named df$ColumnName and df$ColumnName.1
head(df)
CompleteName CompleteName.1
1 Lefebvre Arnaud Lefebvre Schuhl Anne
1.1 Lefebvre Arnaud Abe Lyu
1.2 Lefebvre Arnaud Abe Lyu
1.3 Lefebvre Arnaud Louvet Nicolas
1.4 Lefebvre Arnaud Muller Jean Michel
1.5 Lefebvre Arnaud De Dinechin Florent
I am trying to create labels to see whether the name is the same or not. When I try a small subset it works [1 if they are the same, 0 if not]:
> match(df$CompleteName[1], df$CompleteName.1[1], nomatch = 0)
[1] 0
> match(df$CompleteName[1:10], df$CompleteName.1[1:10], nomatch = 0)
[1] 0 0 0 0 0 0 0 0 0 0
But as soon as I throw the complete columns, it gives me complete different values, which seem nonsense to me:
> match(df$CompleteName, df$CompleteName.1, nomatch = 0)
[1] 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101
[23] 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101
[45] 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101 101
Should I use sapply? I did not figured it out, I tried this with an error:
sapply(df, function(x) match(x$CompleteName, x$CompleteName.1, nomatch = 0))
Please help!!!
From the man page of match,
‘match’ returns a vector of the positions of (first) matches of its first argument in its second.
So your data seem to indicate that the first match of "Lefebvre Arnaud" (the first position in the first argument) is in the row 101. I believe what you intended to do is a simple comparison, so that's just the equality operator ==.
Some sample data:
> a <- rep ("Lefebvre Arnaud", 6)
> b <- c("Abe Lyu", "Abe Lyu", "Lefebvre Arnaud", rep("De Dinechin Florent", 3))
> x <- data.frame(a,b, stringsAsFactors=F)
> x
a b
1 Lefebvre Arnaud Abe Lyu
2 Lefebvre Arnaud Abe Lyu
3 Lefebvre Arnaud Lefebvre Arnaud
4 Lefebvre Arnaud De Dinechin Florent
5 Lefebvre Arnaud De Dinechin Florent
6 Lefebvre Arnaud De Dinechin Florent
> x$a == x$b
[1] FALSE FALSE TRUE FALSE FALSE FALSE
EDIT: Also, you need to make sure that you are comparing apples to apples, so double check the data type of your columns. Use str(df) to see whether the columns are strings or factors. You can either construct the matrix with "stringsAsFactors = FALSE", or convert from factor to character. There are several ways to do that, check here: Convert data.frame columns from factors to characters