如何在 R DataFrame 中按列查找最大字符串长度？

在本文中，我们将了解如何在 R 编程语言中按列查找最大字符串长度。

要在给定数据帧中按列查找最大字符串长度，首先调用 nchar()函数以获取数据帧特定列中存在的所有字符串的长度，然后必须调用 max()函数以获取nchar()函数生成的字符串长度的最大值。 nchar() 和 max()函数是 R 编程语言的基本函数，因此无需导入任何包。

nchar()函数接受一个字符向量作为参数，并返回一个向量，其元素包含 x 对应元素的大小

Syntax:

nchar(x, type = “chars”, allowNA = FALSE, keepNA = NA)

Parameter:

• x: character vector or a vector to be coerced to a character vector. Giving a factor is an error.
• type:character string: partial matching to one of c(“bytes”, “chars”, “width”). See ‘Details’.
• allowNA: logical, should NA be returned for invalid multibyte strings or “bytes”-encoded strings (rather than throwing an error)?
• keepNA:logical: should NA be returned where ever x is NA?

max()函数在提供的数据中找到最大值。

Syntax:

MAX(vector, rank = 1, value = FALSE, rank.adjust = TRUE, forceChoice = FALSE)

Parameter:

• vector: Vector in which maximum/minimum element needs to be identified
• rank:value(s) or rank(s) of maximum values.
• value:  Should value or rank be returned?
• rank.adjust: If the maximum value of a range of ranks exceeds vector length, should this be adjusted?
• forceChoice: In the case of ties, should all results be returned or only one?

示例 1：

R

gfg_data <- data.frame(x = c("geeks", "for", "geeks"),  
                       y = c("I", "Love", "Coding"),
                       z=c("R", "programming ", "language"))
  
max(nchar(gfg_data$y))

输出：

[1] 6

示例 2：

电阻

gfg_data <- data.frame(x = c("geeks", "for", "geeks"),  
                       y = c("I", "Love", "Coding"),
                       z=c("R", "programming ", "language"))
  
max(nchar(gfg_data$z))  

输出：

[1] 12