Merge two columns dataframes

Question

[samira.reuscher]

Hello, i have a question concerning two dataframe that should be merged. To make it more understandable, I broke it down on a simple example.

tabelle1 <- data.frame(genID = c("a","b","c"), 
                  log2FC = c(11,22,33))
tabelle2 <- data.frame(genID = c("b","c","d"), 
                   log2FC = c(44,55,66))

The new dataframe should consist of 3 columns (genID, log2FCtabelle1, log2FCtabelle2) and four rows (a,b,c,d). Missing values should be marked with NA ...

I hope someone can hep me! Thanks.

[zx8754]

Relevant SO post:

• How to join (merge) data frames (inner, outer, left, right)

Answer 1

[ATpoint]

You can use the base function merge like:

merge(tabelle1, tabelle2, by.x = "genID", by.y = "genID", all = TRUE)

genID log2FC.x log2FC.y
a       11       NA
b       22       44
c       33       55
d       NA       66

The by.x/y arguments take the column name of the respective data.frames that shall be used for merging. all=TRUE means to replace missing values by NA.

Answer 2

[nterhoeven]

You can do this with left_join() from the tidyverse package

You should rename the log2FC columns to different names and then run left_join(tabelle1,tabelle2). This will merge the two data frames by the common column (genID).

Take a look at https://stat545.com/join-cheatsheet.html for more info about the different join commands