converting string to numeric in R

Question

I have a problem regarding data conversion using R language.

I have two data that being stored in variables named lung.X and lung.y, below are the description of my data.

> str(lung.X)
 chr [1:86, 1:7129] "  170.0" "  104.0" "   53.7" "  119.0" "  105.5" "  130.0" ...
 - attr(*, "dimnames")=List of 2
  ..$ : chr [1:86] "V3" "V4" "V5" "V6" ...
  ..$ : chr [1:7129] "A28102_at" "AB000114_at" "AB000115_at" "AB000220_at" ...

and

> str(lung.y)
 num [1:86] -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 ...

lung.X is a matrix (row: 86 col: 7129) and lung.y is an array of numbers (86 entries)

Do anyone know how to convert above data into the format below?

> str(lung.X)
     num [1:86, 1:7129] 170 104 53.7 119 105.5 130...

I thought I should do like this

lung.X <- as.numeric(lung.X)

but I got this instead

> str(lung.X)
 num [1:613094] 170 104 53.7 119 105.5 130...

The reason of doing this is because I need lung.X to be numerical only.

Thank you.

Try lung.X[] <- as.numeric(lung.X) or mode(lung.X) <- "numeric". — sgibb
– sgibb, Commented Mar 23, 2016 at 17:13
Just add the dimensions attribute back, e.g. dim(lung.X) <- c(86,7129) — joran
– joran, Commented Mar 23, 2016 at 17:14
@sgibb, the first one does not function but the second one is working! Thank you. — rafidah muhamad
– rafidah muhamad, Commented Mar 23, 2016 at 17:40

Chris Conlan · Accepted Answer · 2016-03-23 17:26:09Z

1

Give this a try: m <- matrix(as.numeric(lung.X), nrow = 86, ncol = 7129)

If you need it in dataframe/list format, df <- data.frame(m)

answered Mar 23, 2016 at 17:26

Chris Conlan

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Chris Conlan Over a year ago

No problem, Rafidah.

sgibb · Accepted Answer · 2016-03-23 17:42:27Z

1

You could change the mode of your matrix to numeric:

## example data
m <- matrix(as.character(1:10), nrow=2,
            dimnames = list(c("R1", "R2"), LETTERS[1:5]))
m
#    A   B   C   D   E
# R1 "1" "3" "5" "7" "9"
# R2 "2" "4" "6" "8" "10"

str(m)
#  num [1:2, 1:5] 1 2 3 4 5 6 7 8 9 10
#  - attr(*, "dimnames")=List of 2
#   ..$ : chr [1:2] "R1" "R2"
#   ..$ : chr [1:5] "A" "B" "C" "D" ...
# NULL

mode(m) <- "numeric"
str(m)
#  num [1:2, 1:5] 1 2 3 4 5 6 7 8 9 10
#  - attr(*, "dimnames")=List of 2
#   ..$ : chr [1:2] "R1" "R2"
#   ..$ : chr [1:5] "A" "B" "C" "D" ...
# NULL
m
#    A B C D  E
# R1 1 3 5 7  9
# R2 2 4 6 8 10

answered Mar 23, 2016 at 17:42

sgibb

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