[英]Subtract 1 letter and number from multiple strings of letters and numbers
我有一個字符串向量:
grid_loc <- c("B2", "B3", "B4", "C2", "C3", "C4", "D2", "D3", "D4")
我怎樣才能重新編碼這些字符串,以便新的矢量看起來像這樣?:
c("A1", "A2", "A3", "B1", "B2", "B3", "C1", "C2", "C3")
如您所見,我希望每個字母和數字字符串都從中減去“一”。 B
變為A
, 3
變為2
等。
在原始數據集中,沒有包含字母A
或數字1
字符串,因此弄清楚如何處理這種情況不是問題。
我試圖使用gsub()
手動重新編碼每個字符串,但由於真實數據集的大小,這太費力了。
另一種方法,使用base R
可以在帶有strsplit
的字母之后split
每個元素,計算每個部分的“減1”操作並重新調整它們:
sapply(strsplit(c(grid_loc, "B20"), "(?<=[B-Z])", perl=TRUE),
function(x) paste0(LETTERS[match(x[1], LETTERS)-1], as.numeric(x[2])-1))
# [1] "A1" "A2" "A3" "B1" "B2" "B3" "C1" "C2" "C3" "A19"
如果原始向量中沒有“A”或“1”,則一個選項是使用gsubfn
減去數字並將字母替換為前面的字母
library(gsubfn)
f1 <- function(x, y) paste0(LETTERS[match(x, LETTERS)-1], as.numeric(y) - 1)
gsubfn('([A-Z])([0-9]+)', f1, grid_loc)
#[1] "A1" "A2" "A3" "B1" "B2" "B3" "C1" "C2" "C3" "A19"
grid_loc <- c("B2", "B3", "B4", "C2", "C3", "C4", "D2", "D3", "D4", "B20")
這里純粹是基礎R方式:
fun=function(x){paste0(LETTERS[match(sub("[^A-Z]+","",x),LETTERS)-1],
as.numeric(sub("\\D+","",x))-1)}
fun(x)
[1] "A1" "A2" "A3" "B1" "B2" "B3" "C1" "C2" "C3" "A19"
數據
x=c("B2", "B3", "B4", "C2", "C3", "C4", "D2", "D3", "D4", "B20")
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