How to add multiple columns to R dataframe from list

Question

I have a dataframe:

df1

a b c
1 1 0
1 1 1
1 1 1

df2

a b c d e f
1 1 0 1 1 1
1 1 1 1 1 1
1 1 1 1 1 1
2 2 2 2 2 2

How can I add new columns to df1 from df2 that aren't in df1? to get:

df2

a b c d e f
1 1 0 0 0 0
1 1 1 0 0 0
1 1 1 0 0 0

I tried:

columns_toadd <- colnames(df1)[!(colnames(df1) %in% colnames(df2))]

for (i in 1:length(columns_toadd)){
  df$columns_toadd[[i]] <- 0
}

But this just gave:

df2

a b c columns_toadd
1 1 0 0 
1 1 1 0 
1 1 1 0

I'd like to do this in base R as I work in an environment with limited packages.

What is definition of new column? Is it column name or content? Also, number of rows differ. — pogibas
– pogibas, Commented Dec 14, 2017 at 13:26
@akrun I just want the names of the columns in df2 not in df1 added onto df1 with a 0 in each row. I'm not focussed on the length atm. — Chuck
– Chuck, Commented Dec 14, 2017 at 13:27
@akrun. Worked perfectly. Thanks a lot. Happy to accept if answer. — Chuck
– Chuck, Commented Dec 14, 2017 at 13:29

akrun · Accepted Answer · 2017-12-14 13:31:17Z

3

We can get the column names that are not in 'df1' using setdiff and assign those to 0

df1[setdiff(names(df2), names(df1))] <- 0

answered Dec 14, 2017 at 13:31

akrun

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