R: Deleting elements from a vector based on element length

问题

How can I delete elements from a vector of strings depending on the number of characters or length of the strings?

df <- c("asdf","fweafewwf","af","","","aewfawefwef","awefWEfawefawef")
> df
[1] "asdf"            "fweafewwf"       "af"              ""                ""                "aewfawefwef"     "awefWEfawefawef"

For example, I may want to delete all elements of df with a length smaller than 5, so the output would be:

> df
[1]"fweafewwf"        "aewfawefwef"     "awefWEfawefawef"

Thanks!

回答1:

Just use nchar:

> df[nchar(df) > 5]
[1] "fweafewwf"       "aewfawefwef"     "awefWEfawefawef"

回答2:

Since nchar works weird with NA's:

nchar(NA)
## [1] 2

I recommend to use stri_length function from stringi package

require(stringi)
df[stri_length(df)>5]

来源：https://stackoverflow.com/questions/23142482/r-deleting-elements-from-a-vector-based-on-element-length