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在for循环中分配不同的类

for-loop class r

3

Joachim Schork · 技术社区 · 10 年前

我想编写一个for循环,在这个循环中,我需要转换数据的某些列的类。帧到字符优先。经过一些操作(与此问题无关)后,我需要将列转换回其原始类。

列到其原始类的转换必须在for循环中完成。我怎么能那样做?

以下是一些数据和循环示例:

# Example data
data <- data.frame(x1 = as.numeric(1:5), x2 = as.factor(7:3))

for(i in 1:ncol(data)) {

  # Save original class.
  class_col_i <- class(data[ , i])

  # Convert column as character.
  data[ , i] <- as.character(data[ , i])

  # (Here I will do some operations, which are irrelevant for this problem.)

  # Here I need to convert the column back to its original class.
  # How can I do that?

  # data[ , i] <- class_col_i... ???
}

class(data$x1) # This should be a numeric
class(data$x2) # This should be a factor

2 回复 | 直到 10 年前

1

3

zx8754 10 年前

使用 match.fun ,请参见此示例:

#dummy data
d <- mtcars
class(d$gear)
# [1] "numeric"

#change to character
classOrg <- class(d$gear)
d$gear <- as.character(d$gear)
class(d$gear)
# [1] "character"

#do some fun stuff
# ... d$gear 

#convert it back
myConvertFun <- match.fun(paste0("as.", classOrg))
d$gear <- myConvertFun(d$gear)
class(d$gear)
# [1] "numeric"

2

0

Bryan Goggin 10 年前

试试这个:

data <- data.frame(x1 = as.numeric(1:5), x2 = as.factor(7:3))
class_col<-NULL
for(i in 1:ncol(data)) {

# Save original class.
class_col[i] <- class(data[ , i])

# Convert column as character.
data[ , i] <- as.character(data[ , i])

# (Here I will do some operations, which are irrelevant for this    
#problem.)

# Here I need to convert the column back to its original class.
# How can I do that?

class(data[ , i]) <- class_col[i]
}

class(data$x1) # This should be a numeric
class(data$x2)