R programming, column reordering

Question

[MAPK]

Hi Guys,

I have two data frames with thousands of columns. The dummy example looks like df1 and df2 below. All the columns names in df2 are in df1. Now, I want these two data frames to combined together in the order where the columns with the same columns names are together as shown in result. Thank you.

df1 <- data.frame(C1=c("A","H","C"),C2=c("0","0","0"), C3=c("A","C","D"),C4=c("A","V","G"))
df1

  C1 C2 C3 C4
1  A  0  A  A
2  H  0  C  V
3  C  0  D  G

df2 <- data.frame(C1=c("A","B","C"),C3=c("G","G","G"))
df2

C1 C3
1  A  G
2  B  G
3  C  G

Result

  C1 C1 C2 C3 C3 C4
1  A    A  0  A    G  A
2  H    B  0  C    G  V
3  C    C  0  D    G  G

[PoGibas]

​MAPK, you have asked a lot of R programming questions recently (examples of those that need to join/extract/compare multiple data tables):

• R programming: genotype concordance
• R programming: compare columns to column and get the mismatch
• R programming: Merge tables
• R programming question: extract all the rows matching Ids
• R programming: match ID in a column and extract all the matching rows
• R programming question: genotyping data table manipulation2

You're welcome to ask R related questions here on biostars. However, I recommend to invest some time into learning R data manipulation tools:

• data.table (Introduction to data.table, data.table cheat sheet)
• reshape(2) (Introduction to reshape2)
• dplyr (Introduction to dplyr)

This should help you to solve problems yourself. Also, you can try to ask R related questions on stackoverflow.com (most of your questions aren't bioinformatics specific, they are just general data structure manipulation problems). Further, it would be nice if you accept answers to your previous questions (if they helped you).

Answer 1

[Brice Sarver]

Assuming which goes where doesn't matter as long as they're grouped, this is pretty easy:

df3 <- cbind(df1, df2)
final <- df3[, order(names(df3))]
final

  C1 C1.1 C2 C3 C3.1 C4
1  A    A  0  A    G  A
2  H    B  0  C    G  V
3  C    C  0  D    G  G

[MAPK]

Sorry this didn't work for the large number of column names. Also, I want them in the same order.

[Sam]

brice.sarver's code should work for any number of column names. The result should have all the names in the same order with all the colnames of the later structure (in his code, it will be df2) be added with the ".1".

If that isn't what you needed, could you please elaborate on what you actually need?