如何在R中给定位置生成给定变量字符的所有可能字符串? [英] How to generate all possible strings given variable characters at given locations in R?

问题描述

给出一个有序的字符串向量，其中每个字符串在该位置显示可能的字符，我如何获得所有可能的字符串组合?

Given an ordered vector of strings where each string shows the possible characters in that position, how can I get all possible combinations of strings?

例如，给定向量:

vec <- c("A", "A", "T", "C", "AG", "ACG", "T", "A", "A")

在给定位置5的情况下，可能的字符串组合可以是"A"，也可以是"A".或"G"，并且6可以是"A"，"C"或"G".是:

The possible string combinations, given positions 5 can be either "A" or "G", and 6 can be "A", "C", or "G" are:

strings <- c("AATCAATAA"
             "AATCACTAA"
             "AATCAGTAA"
             "AATCGATAA"
             "AATCGCTAA"
             "AATCGGTAA")

推荐答案

将向量分割成各个字符，然后使用 expand.grid():

Split your vector into individual characters, then use expand.grid():

vec <- c("A", "A", "T", "C", "AG", "ACG", "T", "A", "A")

strings <- expand.grid(strsplit(vec, ""), stringsAsFactors = FALSE)
strings
#>   Var1 Var2 Var3 Var4 Var5 Var6 Var7 Var8 Var9
#> 1    A    A    T    C    A    A    T    A    A
#> 2    A    A    T    C    G    A    T    A    A
#> 3    A    A    T    C    A    C    T    A    A
#> 4    A    A    T    C    G    C    T    A    A
#> 5    A    A    T    C    A    G    T    A    A
#> 6    A    A    T    C    G    G    T    A    A

这为我们提供了一个数据框，但是我们可以将这些行粘贴在一起以获得单个矢量:

This gives us a data frame, but we can paste the rows together to get a single vector:

apply(strings, 1, paste0, collapse = "")
#> [1] "AATCAATAA" "AATCGATAA" "AATCACTAA" "AATCGCTAA" "AATCAGTAA" "AATCGGTAA"

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