1d:T736,# Overwrite a column in a data.frame based on a matching column in another df Sometimes you want to merge two dataframes and specify that column X in one dataframe should overwrite the same column in the other dataframe. If there is a missing value in the column in the new dataframe, then the value from the old dataframe is kept. ```r merge_dfs_overwrite_col(olddf, newdf, cols, bycol = "well") ``` ## Arguments - `olddf`: The dataframe whose column will be overwritten. - `newdf`: The dataframe that will use its columns to overwrite. - `cols`: The names of the columns that exist in both dataframes that should be overwritten. If not provided, then all columns that are common to both dataframes are used. - `bycol`: The names of the columns to use as the key for the merge. ## Examples ```r df <- function(...) data.frame(..., stringsAsFactors = FALSE) df1 <- df(a = 1:4, b = c("one", NA, "three", "four")) df2 <- df(a = 1:4, b = c("ONE", "TWO", NA, "FOUR")) merge_dfs_overwrite_col(df1, df2, "b", "a") merge_dfs_overwrite_col(df2, df1, "b", "a") df3 <- df(a = 1:3, b = c("one", NA, "three")) df4 <- df(a = 2:4, b = c("TWO", NA, "FOUR")) merge_dfs_overwrite_col(df3, df4, "b", "a") merge_dfs_overwrite_col(df4, df3, "b", "a") df5 <- df(a = 1:3, b = c("one", "two", "three"), c = letters[1:3]) df6 <- df(b = c("ONE", "TWO", "THREE"), c = LETTERS[1:3], a = 1:3) merge_dfs_overwrite_col(df5, df6, "b", "a") merge_dfs_overwrite_col(df6, df5, "b", "a") df7 <- df(a = 1:3, b = c("one", "two", "three")) df8 <- df(a = 1:4) merge_dfs_overwrite_col(df7, df8, "b", "a") merge_dfs_overwrite_col(df8, df7, "b", "a") df9 <- df(a = 1:3, b = c("one", "two", "three"), c = 1:3) df10 <- df(a = 1:3, b = c("ONE", NA, "THREE"), c = 4:6) merge_dfs_overwrite_col(df9, df10, c("b", "c"), "a") merge_dfs_overwrite_col(df10, df9, c("b", "c"), "a") ```1e:T49a,M7.49933 0.25C3.49635 0.25 0.25 3.49593 0.25 7.50024C0.25 10.703 2.32715 13.4206 5.2081 14.3797C5.57084 14.446 5.70302 14.2222 5.70302 14.0299C5.70302 13.8576 5.69679 13.4019 5.69323 12.

merge_dfs_overwrite_col function