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@svigneau
Last active August 29, 2015 13:56
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R function to merge dataframes, appending a specified name for each dataframe to the corresponding columns
## Function ##
# Function to merge dataframes, appending the original dataframe name to the corresponding columns
mergeDeluxe <- function (tomerge, by, all=T, pos="after", sep="_") {
# tomerge: list of dataframes
# by: name of column to use as a join to merge dataframes
# all: whether to keep non-matching lines, as defined in R base "merge" function
# pos: if "after", the dataframe name is appended as a suffix; if "before", it is appended as a prefix
# sep: separator to use when appending dataframe name
# Function to add a label to each element of a vector, except if element is identical to an element of keep
addVecLabel <- function (vec, label, keep) {
# vec, keep: character vectors
# label: character
addEltLabel <- function (elt) {
if (sum(sapply(keep, function (x) elt == x))) {
elt
} else {
if (pos == "after") {
paste(elt, label, sep="_")
} else if (pos == "before") {
paste(label, elt, sep=sep)
}
}
}
sapply(vec, addEltLabel)
}
# Rename columns of each dataframe by appending the dataframe name, except for the join column
tomerge <- lapply(names(tomerge), function (x) {
df <- tomerge[[x]]
vec <- names(df)
label <- x
keep <- by
names(df) <- addVecLabel(vec, label, keep)
df
}
)
# Merge all dataframes by column by
Reduce(function (x, y) merge(x, y, by=by, all=all), tomerge)
}
## Usage ##
# List of dataframes to merge (here df1 and df2)
#tomerge <- list(label1=df1, label2=df2)
# Join columns for merge
#by <- c("Gene", "Chr", "Start", "End", "Strand")
# Merge
#mergeDeluxe(tomerge, by)
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