具有多個列和數據幀的函數gsub R

Question

我有兩個數據框具有相同的列名。我想在多個數據框的2列中替換某個表達式。所以我寫了下面的代碼：

dat <- data.frame(n = 1:19, des = c("Some very long text", "Some very lang test", "Some vary long text", "Some veri long text", "Another very long text", "Anather very long text", "Another very long text", "Different text", "Diferent text", "More text", "More test", "Much more text", "Muh more text", "Some other long text", "Some otoher long text", "Some more text", "Same more text", "New text", "New texd"), x = c("other text", "bad text", "wrong text", "very bad text", "very nice text","text", "text", "text", "text", "text", "text", "text", "text", "text", "text", "text", "text", "text", "text")) 

dat1 <- data.frame(n = 1:5, des = c("very Some long text", "text Some very long", "Some very long text", "long text Some very", "very long Some text"), x = c("crazy text", "very crazy text", "boring text", "very exciting text","ext")) 

repla <- function(dat){ 
vari <- c(which(names(dat) == "x"),which(names(dat) == "des")) 
    for (i in vari){ 
    dat[,i] <<- gsub("very", "0", dat[,i]) 
    } 
} 

但是爲什麼重放功能不工作？

Answer 1

你的函數定義改成這樣：

repla <- function(dat){ 
vari <- c(which(names(dat) == "x"),which(names(dat) == "des")) 
    for (i in vari) { 
     # don't use the parent scope assignment operator here 
     # instead, just modify the local variable 
     dat[,i] <- gsub("very", "0", dat[,i]) 
    } 

    # return modified data frame to the caller 
    return(dat) 
} 

，然後用它是這樣的：

dat1 <- repla(dat1) 

這裏是dat1輸出使用此代碼後：

> dat1 
    n    des    x 
1 1 0 Some long text  crazy text 
2 2 text Some 0 long 0 crazy text 
3 3 Some 0 long text  boring text 
4 4 long text Some 0 0 exciting text 
5 5 0 long Some text    ext