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rdataframecomparecell

Can i exchange two different cell data in R?

i got two dataframes in R. And i want to compare two dataframe and change the cell data.

data1
a
b
data11 data21
c 1
a 2

if i compare [data1] and [data11], if "a" is exist in range [data11], then i change the "a" to "2" which is same row in data21.

Solution

  • I'm assuming you are working with two dataframes:

    df1 <- data.frame(col1 = c("a", "b"))
df1
#>   col1
#> 1    a
#> 2    b

df2 <- data.frame(data11 = c("c", "a"), data21 = c(1, 2))
df2
#>   data11 data21
#> 1      c      1
#> 2      a      2

    If you use ifelse(), the indexing might be incorrect (we would expect the results to be "2" "b" here):

    ifelse(df1$col1 %in% df2$data11, df2$data21, df1$col1)
#> [1] "1" "b"

    So you can use merge() instead:

    df3 <- merge(df1, df2, by.x = "col1", by.y = "data11", all.x = TRUE)
df3$data21 <- ifelse(is.na(df3$data21), df3$col1, df3$data21)
df3
#>   col1 data21
#> 1    a      2
#> 2    b      b