Creating an R dataframe row-by-row

user_377031 0
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I would like to construct a dataframe row-by-row in R. I've done some searching, and all I came up with is the suggestion to create an empty list, keep a list index scalar, then each time add to the list a single-row dataframe and advance the list index by one. Finally, do.call(rbind,) on the list.

While this works, it seems very cumbersome. Isn't there an easier way for achieving the same goal?

Obviously I refer to cases where I can't use some apply function and explicitly need to create the dataframe row by row. At least, is there a way to push into the end of a list instead of explicitly keeping track of the last index used?

dataframe r list
8 Answers

Dirk Eddelbuettel's answer is the best; here I just note that you can get away with not pre-specifying the dataframe dimensions or data types, which is sometimes useful if you have multiple data types and lots of columns:

row1<-list("a",1,FALSE) #use 'list', not 'c' or 'cbind'!
row2<-list("b",2,TRUE)  

df<-data.frame(row1,stringsAsFactors = F) #first row
df<-rbind(df,row2) #now this works as you'd expect.
user_30912860

I've found this way to create dataframe by raw without matrix.

With automatic column name

df<-data.frame(
        t(data.frame(c(1,"a",100),c(2,"b",200),c(3,"c",300)))
        ,row.names = NULL,stringsAsFactors = FALSE
    )

With column name

df<-setNames(
        data.frame(
            t(data.frame(c(1,"a",100),c(2,"b",200),c(3,"c",300)))
            ,row.names = NULL,stringsAsFactors = FALSE
        ), 
        c("col1","col2","col3")
    )
user_104895620

Depending on the format of your new row, you might use tibble::add_row if your new row is simple and can specified in "value-pairs". Or you could use dplyr::bind_rows, "an efficient implementation of the common pattern of do.call(rbind, dfs)".

user_46630080
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