R语言 数据框架中查找最大值的索引

在这篇文章中，我们将看到如何在R编程语言中从一个数据框架中找到最大值的索引

我们可以使用 which.max() 函数找到数据框中的最大值索引。

语法

which.max(dataframe_namecolumnname)

““用于访问数据框架的特定列。

下面给出了各种实现，描述了各种数据类型和情况，以帮助你更好地理解。

例1 :

# vector 1
data1=c("sravan","bobby","pinkey","rohith","gnanesh")
 
# vector 2
data2=c(98,78,79,97,89)
 
# creating a dataframe with names and marks
# using above vectors
final <- data.frame(names=data1,marks=data2)
                    
print(final)
 
# display the maximum value index in 2 nd column
# (marks column) in a dataframe
print(paste("highest index is : ",which.max(final$marks)))

输出

如果有一个以上的最大值，那么它将返回第一个被重复的数字的索引。

例2 :

# vector 1
data1=c("sravan","bobby","pinkey","rohith",
        "gnanesh",'divya',"satwik","chandu")
 
# vector 2
data2=c(98,78,79,97,89,89,99,99)
 
# creating a dataframe with names and marks
# using above vectors
final <- data.frame(names=data1,marks=data2)
                    
print(final)
 
print(paste("highest index is : ",which.max(final$marks)))

输出

如果数据是字符类型的，它将使用ASCII值找到最大值。

例3 :

# vector 1
data1=c("sravan","bobby","pinkey","rohith",
        "gnanesh",'divya',"satwik","zhandu")
 
# vector 2
data2=c(98,78,79,97,89,89,99,99)
 
# creating a dataframe with names and marks
# using above vectors
final <- data.frame(names=data1,marks=data2)
                    
print(final)
 
# display maximum value index for character values
print(paste("highest index is : ",which.max(final$names)))

输出

例4 :

# vector 1 that contains NA values as characters
data1=c(NA,"sravan",NA,NA,NA)
 
# vector 2 contains all data
data2=c(102,98,98,102,102)
 
# creating a dataframe with names and marks
# using above vectors
final <- data.frame(names=data1,marks=data2)
                    
print(final)
 
# display maximum value index for character values
print(paste("highest index is : ",which.max(finalnames)))
 
# display maximum value index for  marks values
print(paste("highest index is : ",which.max(finalmarks)))

输出

如果包含所有数值的行是相同的，那么所有数值都是高的。所以它将返回第一个元素的索引。

例5 :

# vector contains all same data
data2=c(102,102,102,102,102)
 
# creating a dataframe marks using above vector
final <- data.frame(marks=data2)
                    
print(final)
 
# display maximum value index for  marks values
print(paste("highest index is : ",which.max(final$marks)))

输出

如果数据包含NA值，那么它将返回空值。

例6 :

# vector contains all NA's
data2=c(NA,NA)
 
# creating a dataframe marks using
# above vector
final <- data.frame(marks=data2)
                    
print(final)
 
# display maximum value index for  marks values
print(paste("highest index is : ",which.max(final$marks)))

输出