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Simultaneously merge multiple data.frames in a list
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Closed 6 years ago.
I need to merge multiple dataframe with the matching values in column A. What is the most efficient way to do this and get the result.
df1
A B C
2 x r
1 c r
3 y t
df2
A D E
3 e y
1 t t
2 y t
df3
A F G
1 g y
2 f y
3 h k
result
A B C D E F G
1 c r t t g y
2 x r y t f y
3 y t y t h k
One solution is to use dplyr package and it's inner_join as follows:
library(dplyr)
df <- inner_join(df1, df2)
df <- inner_join(df, df3)
Resulting output is:
df
A B C D E F G
1 2 x r y t f y
2 1 c r t t g y
3 3 y t e y h k
Note, inner_join keeps only rows where A matches.
If you want it arranged by column A, you can add this line:
arrange(df, A)
A B C D E F G
1 1 c r t t g y
2 2 x r y t f y
3 3 y t e y h k
To merge a variable length list of data frames, it appears Reduce can be helpful along with the above inner_join:
df <- Reduce(inner_join, list(df1, df2, df3))
arrange(df, A)
A B C D E F G
1 1 c r t t g y
2 2 x r y t f y
3 3 y t e y h k
Related
I got these two data frames:
a <- c('A','B','C','D','E','F','G','H')
b <- c(1,2,1,3,1,3,1,6)
c <- c('K','K','H','H','K','K','H','H')
frame1 <- data.frame(a,b,c)
a <- c('A','A','B','B','C','C','D','D','E','E','F','F','G','H','H')
d <- c(5,5,6,3,1,9,1,0,2,3,6,5,5,5,4)
e <- c('W','W','D','D','D','D','W','W','D','D','W','W','D','W','W')
frame2<- data.frame(a,d,e)
And now I want to include the column 'e' from 'frame2' into 'frame1' depending on the matching value in column 'a' of both data frames. Note: 'e' is the same for all rows with the same value in 'a'.
The result should look like this:
a b c e
1 A 1 K W
2 B 2 K D
3 C 1 H D
4 D 3 H W
5 E 1 K D
6 F 3 K W
7 G 1 H D
8 H 6 H W
Any sugestions?
You can use match to matching value in column 'a' of both data frames:
frame1$e <- frame2$e[match(frame1$a, frame2$a)]
frame1
# a b c e
#1 A 1 K W
#2 B 2 K D
#3 C 1 H D
#4 D 3 H W
#5 E 1 K D
#6 F 3 K W
#7 G 1 H D
#8 H 6 H W
or using merge:
merge(frame1, frame2[!duplicated(frame2$a), c("a", "e")], all.x=TRUE)
you can perform join operation on 'a' column of both dataframes and take those values only which are matched. you can do left join , and after that remove 'a' column from 2nd dataframe and also remove rest of the columns, which are'nt needed from 2nd dataframe.
Using dplyr :
library(dplyr)
frame2 %>%
distinct(a, e, .keep_all = TRUE) %>%
right_join(frame1, by = 'a') %>%
select(-d) %>%
arrange(a)
# a e b c
#1 A W 1 K
#2 B D 2 K
#3 C D 1 H
#4 D W 3 H
#5 E D 1 K
#6 F W 3 K
#7 G D 1 H
#8 H W 6 H
I used rbind to join 2 dataframes, with a column denoting its source, resulting in
from | to | source
1 A B X
2 C D Y
3 B A Y
...
I would like to look for overlapping pairs, regardless of "order", combine those pairs, then edit the source column to something else, e.g. "Z".
In the above example, rows 1 and 3 would be flagged as overlapping, so they will be combined and modified.
So the desired output would look something like
from | to | source
1 A B Z
2 C D Y
...
How can this be done?
You can try the code below
unique(
transform(
transform(
df,
from = pmin(from, to),
to = pmax(from, to)
),
source = ave(source, from, to, FUN = function(x) ifelse(length(x) > 1, "Z", x))
)
)
which gives
from to source
1 A B Z
2 C D Y
Example
set.seed(1)
df=data.frame(
"from"=sample(LETTERS[1:4],10,replace=T),
"to"=sample(LETTERS[1:4],10,replace=T),
"source"=sample(c("X","Y"),10,replace=T)
)
from to source
1 A C X
2 D C X
3 C A X
4 A A X
5 B A X
6 A B X
7 C B Y
8 C B X
9 B B X
10 B C Y
and then
tmp=t(
apply(df,1,function(x){
sort(x[1:2])
})
)
t1=duplicated(tmp,fromLast=F)
t2=duplicated(tmp,fromLast=T)
df[t2,"source"]="Z"
df[!t1,]
from to source
1 A C Z
2 D C X
4 A A X
5 B A Z
7 C B Z
9 B B X
I want to add a total row (as in the Excel tables) while writing my data.frame in a worksheet.
Here is my present code (using openxlsx):
writeDataTable(wb=WB, sheet="Data", x=X, withFilter=F, bandedRows=F, firstColumn=T)
X contains a data.frame with 8 character variables and 1 numeric variable. Therefore the total row should only contain total for the numeric row (it will be best if somehow I could add the Excel total row feature, like I did with firstColumn while writing the table to the workbook object rather than to manually add a total row).
I searched for a solution both in StackOverflow and the official openxslx documentation but to no avail. Please suggest solutions using openxlsx.
EDIT:
Adding data sample:
A B C D E F G H I
a b s r t i s 5 j
f d t y d r s 9 s
w s y s u c k 8 f
After Total row:
A B C D E F G H I
a b s r t i s 5 j
f d t y d r s 9 s
w s y s u c k 8 f
na na na na na na na 22 na
library(janitor)
adorn_totals(df, "row")
#> A B C D E F G H I
#> a b s r t i s 5 j
#> f d t y d r s 9 s
#> w s y s u c k 8 f
#> Total - - - - - - 22 -
If you prefer empty space instead of - in the character columns you can specify fill = "" or fill = NA.
Assuming your data is stored in a data.frame called df:
df <- read.table(text =
"A B C D E F G H I
a b s r t i s 5 j
f d t y d r s 9 s
w s y s u c k 8 f",
header = TRUE,
stringsAsFactors = FALSE)
You can create a row using lapply
totals <- lapply(df, function(col) {
ifelse(!any(!is.numeric(col)), sum(col), NA)
})
and add it to df using rbind()
df <- rbind(df, totals)
head(df)
A B C D E F G H I
1 a b s r t i s 5 j
2 f d t y d r s 9 s
3 w s y s u c k 8 f
4 <NA> <NA> <NA> <NA> <NA> <NA> <NA> 22 <NA>
I have a data frame that has one value in each cell, but my last column is a list.
Example. Here there are 3 columns. X and Y columns have one value in each row. But column Z is actually a list. It can have multiple values in each cell.
X Y Z
1 a d h, i, j
2 b e j, k
3 c f l, m, n, o
I need to create this:
X Y Z
1 a d h
2 a d i
3 a d j
4 b e j
4 b e k
5 c f l
6 c f m
7 c f n
8 c f o
Can someone help me figure this out ? I am not sure how to use melt or dcast or any other function for this.
Thanks.
unnest from tidyr works
library(tidyr)
unnest(dat, Z)
I have two dataframe in R.
dataframe 1
A B C D E F G
1 2 a a a a a
2 3 b b b c c
4 1 e e f f e
dataframe 2
X Y Z
1 2 g
2 1 h
3 4 i
1 4 j
I want to match dataframe1's column A and B with dataframe2's column X and Y. It is NOT a pairwise comparsions, i.e. row 1 (A=1 B=2) are considered to be same as row 1 (X=1, Y=2) and row 2 (X=2, Y=1) of dataframe 2.
When matching can be found, I would like to add columns C, D, E, F of dataframe1 back to the matched row of dataframe2, as follows: with no matching as na.
Final dataframe
X Y Z C D E F G
1 2 g a a a a a
2 1 h a a a a a
3 4 i na na na na na
1 4 j e e f f e
I can only know how to do matching for single column, however, how to do matching for two exchangable columns and merging two dataframes based on the matching results is difficult for me. Pls kindly help to offer smart way of doing this.
For the ease of discussion (thanks for the comments by Vincent and DWin (my previous quesiton) that I should test the quote.) There are the quota for loading dataframe 1 and 2 to R.
df1 <- data.frame(A = c(1,2,4), B=c(2,3,1), C=c('a','b','e'),
D=c('a','b','e'), E=c('a','b','f'),
F=c('a','c','f'), G=c('a','c', 'e'))
df2 <- data.frame(X = c(1,2,3,1), Y=c(2,1,4,4), Z=letters[7:10])
The following works, but no doubt can be improved.
I first create a little helper function that performs a row-wise sort on A and B (and renames it to V1 and V2).
replace_index <- function(dat){
x <- as.data.frame(t(sapply(seq_len(nrow(dat)),
function(i)sort(unlist(dat[i, 1:2])))))
names(x) <- paste("V", seq_len(ncol(x)), sep="")
data.frame(x, dat[, -(1:2), drop=FALSE])
}
replace_index(df1)
V1 V2 C D E F G
1 1 2 a a a a a
2 2 3 b b b c c
3 1 4 e e f f e
This means you can use a straight-forward merge to combine the data.
merge(replace_index(df1), replace_index(df2), all.y=TRUE)
V1 V2 C D E F G Z
1 1 2 a a a a a g
2 1 2 a a a a a h
3 1 4 e e f f e j
4 3 4 <NA> <NA> <NA> <NA> <NA> i
This is slightly clunky, and has some potential collision and order issues but works with your example
df1a <- df1; df1a$A <- df1$B; df1a$B <- df1$A #reverse A and B
merge(df2, rbind(df1,df1a), by.x=c("X","Y"), by.y=c("A","B"), all.x=TRUE)
to produce
X Y Z C D E F G
1 1 2 g a a a a a
2 1 4 j e e f f e
3 2 1 h a a a a a
4 3 4 i <NA> <NA> <NA> <NA> <NA>
One approach would be to create an id key for matching that is order invariant.
# create id key to match
require(plyr)
df1 = adply(df1, 1, transform, id = paste(min(A, B), "-", max(A, B)))
df2 = adply(df2, 1, transform, id = paste(min(X, Y), "-", max(X, Y)))
# combine data frames using `match`
cbind(df2, df1[match(df2$id, df1$id),3:7])
This produces the output
X Y Z id C D E F G
1 1 2 g 1 - 2 a a a a a
1.1 2 1 h 1 - 2 a a a a a
NA 3 4 i 3 - 4 <NA> <NA> <NA> <NA> <NA>
3 1 4 j 1 - 4 e e f f e
You could also join the tables both ways (X == A and Y == B, then X == B and Y == A) and rbind them. This will produce duplicate pairs where one way yielded a match and the other yielded NA, so you would then reduce duplicates by slicing only a single row for each X-Y combination, the one without NA if one exists.
library(dplyr)
m <- left_join(df2,df1,by = c("X" = "A","Y" = "B"))
n <- left_join(df2,df1,by = c("Y" = "A","X" = "B"))
rbind(m,n) %>%
group_by(X,Y) %>%
arrange(C,D,E,F,G) %>% # sort to put NA rows on bottom of pairs
slice(1) # take top row from combination
Produces:
Source: local data frame [4 x 8]
Groups: X, Y
X Y Z C D E F G
1 1 2 g a a a a a
2 1 4 j e e f f e
3 2 1 h a a a a a
4 3 4 i NA NA NA NA NA
Here's another possible solution in base R. This solution cbind()s new key columns (K1 and K2) to both data.frames using the vectorized pmin() and pmax() functions to derive the canonical order of the key columns, and merges on those:
merge(cbind(df2,K1=pmin(df2$X,df2$Y),K2=pmax(df2$X,df2$Y)),cbind(df1,K1=pmin(df1$A,df1$B),K2=pmax(df1$A,df1$B)),all.x=T)[,-c(1:2,6:7)];
## X Y Z C D E F G
## 1 1 2 g a a a a a
## 2 2 1 h a a a a a
## 3 1 4 j e e f f e
## 4 3 4 i <NA> <NA> <NA> <NA> <NA>
Note that the use of pmin() and pmax() is only possible for this problem because you only have two key columns; if you had more, then you'd have to use some kind of apply+sort solution to achieve the canonical key order for merging, similar to what #Andrie does in his helper function, which would work for any number of key columns, but would be less performant.