Convert character matrix into numeric matrix

Question

I have a 7 by 31 character matrix called `extra4` and its structure looks like this: ``` > str(extra4) chr [1:7, 1:31] "36.88 " " 45.48 " " 52.46 " " 111.31 " " 138.45 " " 121.09 " " 122.62" ... - attr(*, "dimnames")=List of 2 ..$ : chr [1:7] "1990" "1991" "1992" "1993" ... ..$ : chr [1:31] "1" "2" "3" "4" ... ``` After reading similar questions in SO I've tried the following but I've failed: ``` >matrix(as.numeric(unlist(extra4)),nrow=nrow(extra4)) Warning message: In matrix(as.numeric(unlist(extra4)), nrow = nrow(extra4)) : NAs introduced by coercion ``` and also I've tried ``` > class(extra4)<-"numeric" Warning message: In class(extra4) <- "numeric" : NAs introduced by coercion > extra4<-apply(extra4, 1, as.numeric) Warning messages: 1: In apply(extra4, 1, as.numeric) : NAs introduced by coercion 2: In apply(extra4, 1, as.numeric) : NAs introduced by coercion 3: In apply(extra4, 1, as.numeric) : NAs introduced by coercion 4: In apply(extra4, 1, as.numeric) : NAs introduced by coerc…

Accepted Answer

There isn't really a problem here at all, not with most options I tried. You are getting Warnings but these pertain to the `"NA"` strings, which because they aren't `NA` nor a number stored in a string, R doesn't know what to do with them and changes these to `NA`. This is all the warning is telling you. Hence

```
apply(extra4, 2, as.numeric)
sapply(extra4, as.numeric)
class(extra4) <- "numeric"
storage.mode(extra4) <- "numeric"
```

all work and all warn about the " NA " values (or variants thereof) in column 22 of `extra4`:

```
Warning message:
In storage.mode(m) <- "numeric" : NAs introduced by coercion
```

but these are just warnings and in this case can be ignored. If they trouble you, you could wrap the call in `suppressWarnings()`

```
> suppressWarnings(storage.mode(m) <- "numeric")
```

but that is dangerous as it will stop all warnings, not just the one about the `NA`s.

Convert character matrix into numeric matrix

Solution

Problem