I have the following data.table:
我有以下数据。
id fShort
1 432-12 1245
2 3242-12 453543
3 324-32 45543
4 322-34 45343
5 2324-34 13543
DT <- data.table(
id=c("432-12", "3242-12", "324-32", "322-34", "2324-34"),
fShort=c("1245", "453543", "45543", "45343", "13543"))
and the following list:
和下面的列表:
filenames <- list("3242-124342345.png", "432-124343.png", "135-13434.jpeg")
I would like to create a new column "fComplete" that includes the complete filename from the list. For this the values of column "id" need to be matched with the filename-list. If the filename starts with the "id" string, the complete filename should be returned. I use the following regex
我想创建一个新的列“fComplete”，其中包含列表中的完整文件名。为此，需要将列“id”的值与fil珐琅-list进行匹配。如果文件名以“id”字符串开头，则应返回完整的文件名。我使用下面的regex
t <- grep("432-12","432-124343.png",value=T)
that return the correct filename.
返回正确的文件名。
This is how the final table should look like:
最后的表格应该是这样的:
id fShort fComplete
1 432-12 1245 432-124343.png
2 3242-12 453543 3242-124342345.png
3 324-32 45543 NA
4 322-34 45343 NA
5 2324-34 13543 NA
DT2 <- data.table(
id=c("432-12", "3242-12", "324-32", "322-34", "2324-34"),
fshort=c("1245", "453543", "45543", "45343", "13543"),
fComplete = c("432-124343.png", "3242-124342345.png", NA, NA, NA))
I tried using apply and data.table approaches but I always get warnings like
我尝试使用apply和data。表方法，但我总是得到类似的警告
argument 'pattern' has length > 1 and only the first element will be used
What is a simple approach to accomplish this?
有什么简单的方法可以做到这一点?
2 个解决方案
#1
3
Here's a data.table solution:
这里有一个数据。表解决方案:
DT[ , fComplete := lapply(id, function(x) {
m <- grep(x, filenames, value = TRUE)
if (!length(m)) NA else m})]
id fShort fComplete
1: 432-12 1245 432-124343.png
2: 3242-12 453543 3242-124342345.png
3: 324-32 45543 NA
4: 322-34 45343 NA
5: 2324-34 13543 NA
#2
1
In my experience with similar functions, sometimes the regex functions return a list, so you have to consider that in the apply - I usually do an example manually Also apply will not always in y experience on its own return something that always works into a data.frame,sometimes I had to use lap ply, and or unlist and data.frame to modify it
与类似的功能在我的经验中,有时regex函数返回一个列表,所以你必须考虑到在应用——我通常做一个例子还手动应用不会总是在y的经验自行返回的东西总是data.frame,有时我必须用一圈厚度,或unlist data.frame修改它
Here is an answer - I am not familiar with data.tables and I was having issues with the filenames being in a list, but with some transformations this works. I worked it out by seeing what apply was outputting and adding the [1] to get the piece I needed
这里有一个答案——我不熟悉数据。表和我遇到了文件名在列表中的问题，但是通过一些转换，这个方法可以工作。我通过查看应用的输出和添加[1]来得到我需要的部分来解决这个问题
DT <- data.frame(
id=c("432-12", "3242-12", "324-32", "322-34", "2324-34"),
fShort=c("1245", "453543", "45543", "45343", "13543"))
filenames <- list("3242-124342345.png", "432-124343.png", "135-13434.jpeg")
filenames1 <- unlist(filenames)
x<-apply(DT[1],1,function(x) grep(x,filenames1)[1])
DT$fielname <- filenames1[x]
#1
3
Here's a data.table solution:
这里有一个数据。表解决方案:
DT[ , fComplete := lapply(id, function(x) {
m <- grep(x, filenames, value = TRUE)
if (!length(m)) NA else m})]
id fShort fComplete
1: 432-12 1245 432-124343.png
2: 3242-12 453543 3242-124342345.png
3: 324-32 45543 NA
4: 322-34 45343 NA
5: 2324-34 13543 NA
#2
1
In my experience with similar functions, sometimes the regex functions return a list, so you have to consider that in the apply - I usually do an example manually Also apply will not always in y experience on its own return something that always works into a data.frame,sometimes I had to use lap ply, and or unlist and data.frame to modify it
与类似的功能在我的经验中,有时regex函数返回一个列表,所以你必须考虑到在应用——我通常做一个例子还手动应用不会总是在y的经验自行返回的东西总是data.frame,有时我必须用一圈厚度,或unlist data.frame修改它
Here is an answer - I am not familiar with data.tables and I was having issues with the filenames being in a list, but with some transformations this works. I worked it out by seeing what apply was outputting and adding the [1] to get the piece I needed
这里有一个答案——我不熟悉数据。表和我遇到了文件名在列表中的问题，但是通过一些转换，这个方法可以工作。我通过查看应用的输出和添加[1]来得到我需要的部分来解决这个问题
DT <- data.frame(
id=c("432-12", "3242-12", "324-32", "322-34", "2324-34"),
fShort=c("1245", "453543", "45543", "45343", "13543"))
filenames <- list("3242-124342345.png", "432-124343.png", "135-13434.jpeg")
filenames1 <- unlist(filenames)
x<-apply(DT[1],1,function(x) grep(x,filenames1)[1])
DT$fielname <- filenames1[x]