How to match and replace elements between two dataframes-CFANZ编程社区

df1<-data.frame(id=c(1,2,3,4), value=c(10,20,30,40))

df2<-data.frame(col1=c(1,2,3,4), col2=c(4,3,2,1))

df2[] <- lapply(df2, function(x) {
   inds <- match(x, df1$id)
   ifelse(is.na(inds),x, df1$value[inds]) 
})

How to match and replace elements between two dataframes_sed

================================================

df <-(fruits =("apple","orange","pineapple","banana","grape"),=FALSE)

df_rep <-(eng =("apple","orange","grape"),=("manzana","naranja","uva"),=FALSE)

df2 <- merge(df, df_rep, by.x = 'fruits', by.y = 'eng', all.x = TRUE)

df2$fruits <- ifelse(is.na(df2$esp), df2$fruits, df2$esp)

How to match and replace elements between two dataframes_sed_02

================================================

a <- data.frame(id=letters[1:4], age=c(18,NA,9,NA), sex=c("M","F","F","M"))

b <- data.frame(id=c("a","b","d"), age=c(18,32,20))

library(data.table)
setDT(a)[b, agei := i.age, on='id'][is.na(age), age := agei][,agei:= NULL][]
a

================================================

library(dplyr)

dt1 <- read.table(text = "
SAMPLE_ID CLASS_ID CLASS VALUE
1         0        0      5
2         0        0      5
3         0        0      3
4         0        0      6
5         0        0      6
6         0        0      3
", header = TRUE, stringsAsFactors = FALSE)

dt2 <- read.table(text = "
SAMPLE_ID REF_VAL CLASS_ID CLASS
1        33        2      cloud
2        45        3      water
3        NA        3      water
4        NA        4      forest
", header = TRUE, stringsAsFactors = FALSE)

dt3 <- read.table(text = "
SAMPLE_ID CLASS_ID CLASS STRATA
5         3       NA      20
6         3      water    19
", header = TRUE, stringsAsFactors = FALSE)

dt <- dt1[,c("SAMPLE_ID", "VALUE")]
dt <- left_join(dt, dplyr::bind_rows(dt2, dt3))
dt <- select(dt, SAMPLE_ID, CLASS_ID, CLASS, VALUE)

How to match and replace elements between two dataframes_sed_03

================================================

REF

https://stackoverflow.com/questions/51439076/how-to-match-and-replace-elements-between-two-dataframes

https://stackoverflow.com/questions/51614901/r-conditional-replacement-using-two-data-frames

https://stackoverflow.com/questions/33954292/merge-two-data-frame-and-replace-the-na-value-in-r

https://stackoverflow.com/questions/48470586/r-replace-values-in-dataframe-based-on-two-matching-conditions

https://stackoverflow.com/questions/29809512/replace-values-between-two-data-frames-in-r

https://stackoverflow.com/questions/50258443/fast-way-for-string-matching-and-replacement-from-another-dataframe-in-r