使用R语言format函数：仅为超宽最后一行添加空格的实现问询

我在用R的format函数处理数据时，遇到一个情况：只有最后一行的内容超出了设定的宽度范围，我希望仅为该行添加空格来对齐，其他行保持原有格式。我写了如下代码：

a <- c(1 : 8)
b <- rep(43, 8)
c <- c(16, 19, 20, 22, 28, 28, 28, 28)
d <- c(-2814, -1474, -1012, -2, -1.6739, -0.012139, -0.31399, -2.5296E-06)
e <- c("Others 2107", "Others 2110", "Others 2111", "Others 2113", "Others 2119", "Others 2119", "Others 2119", "Others 2119")

a1 <- format(a, width = 10, justify = "right")
b1 <- format(cbind(b, c), width = 9, justify = "right")
c1 <- format(d, width = 10, justify = "right")
d1 <- format(e, justify = "left")

lines <- cbind(a1, b1, c1, d1)
lines <- apply(lines, 1, paste0, collapse = " ")

print(lines)

当前输出结果：

1        43        16       -2814 Others 2107
         2        43        19       -1474 Others 2110
         3        43        20       -1012 Others 2111
         4        43        22          -2 Others 2113
         5        43        28     -1.6739 Others 2119
         6        43        28   -0.012139 Others 2119
         7        43        28    -0.31399 Others 2119
         8        43        28 -2.5296E-06 Others 2119

我期望得到的结果：

1        43        16      -2814 Others 2107
         2        43        19      -1474 Others 2110
         3        43        20      -1012 Others 2111
         4        43        22         -2 Others 2113
         5        43        28    -1.6739 Others 2119
         6        43        28  -0.012139 Others 2119
         7        43        28   -0.31399 Others 2119
         8        43        28 -2.5296E-06 Others 2119

解决方案 #

核心思路是先计算出d列所有元素格式化后的最大宽度，让前面的行按该最大宽度减一的尺寸格式化，最后一行用最大宽度，实现仅为最后一行补空格对齐的效果。

修改后的代码如下：

a <- c(1 : 8)
b <- rep(43, 8)
c <- c(16, 19, 20, 22, 28, 28, 28, 28)
d <- c(-2814, -1474, -1012, -2, -1.6739, -0.012139, -0.31399, -2.5296E-06)
e <- c("Others 2107", "Others 2110", "Others 2111", "Others 2113", "Others 2119", "Others 2119", "Others 2119", "Others 2119")

# 计算d列所有元素格式化后的最大宽度
formatted_d <- format(d, justify = "right")
max_width <- max(nchar(formatted_d))
# 前7行用max_width-1的宽度，最后一行用max_width
c1 <- ifelse(seq_along(d) < length(d), 
             format(d, width = max_width - 1, justify = "right"),
             format(d, width = max_width, justify = "right"))

a1 <- format(a, width = 10, justify = "right")
b1 <- format(cbind(b, c), width = 9, justify = "right")
d1 <- format(e, justify = "left")

lines <- cbind(a1, b1, c1, d1)
lines <- apply(lines, 1, paste0, collapse = " ")

print(lines)

运行这段代码后，就能得到期望的输出效果。

内容的提问来源于stack exchange，提问作者YUHWAN SEO