英文:
Filter vector based on values from a column
问题
让我们假设我有一个向量
letters <- c("a", "b", "c", "d", "e")
我还有一个名为 df 的表，其中包含一个列，其中包含值，如 a_1, b_2, c_3, 等等。
我该如何过滤 letters，只保留在 df 的列中可用的字符。
例如，letters <- c("a", "b", "c", "d", "e", "f")，df$column 的值为 "a_1", "d_3", "b_7"。letters 现在应该变成 c("a", "b", "d")。
英文:
Let's say I have a vector
letters <- c("a", "b", "c", "d", "e")
I also have a table named df which has a column containing values such as "a_1", "b_2", c_3", ...etc.
How do I filter letters to only keep characters that are available in the column from df.
For example, letters <- c("a", "b", "c", "d", "e", "f") and df$column values are "a_1", "d_3", "b_7". letters should now become c("a", "b", "d").
答案1
得分: 1
我们可以从列中移除_和一个或多个数字(\\d+)，使用%in%创建一个逻辑向量并对letters对象进行子集操作。
letters[letters %in% sub("_\\d+", "", df$column)]
[1] "a" "b" "d"
数据
df <- data.frame(column = c("a_1", "d_3", "b_7"))
英文:
We may remove the _ and one or more digits (\\d+) from the column, use %in% to create a logical vector and subset the letters object
letters[letters %in% sub("_\\d+", "", df$column)]
[1] "a" "b" "d"
data
df <- data.frame(column = c("a_1", "d_3", "b_7"))
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