R mistreat a number as a character - r

Question

I am trying to read a series of text files into R. These files are of the same form, at least appear to be of the same form. Everything is fine except one file. When I read that file, R treated all numbers as characters. I used as.numeric to convert back, but the data value changed. I also tried to convert text file to csv and then read into R, but it did not work, either. Did any one have such problem before, please? How to fix it, please? Thank you!
The data is from Human Mortality Database. I cannot attach the data here due to copyright issue. But everyone can register through HMD and download data (www.mortality.org). As an example, I used Australian and Belgium 1 by 1 exposure data.
My codes are as follows:
AUSe<-read.table("AUS.Exposures_1x1.txt",skip=1,header=TRUE)[,-5]
BELe<-read.table("BEL.Exposures_1x1.txt",skip=1,header=TRUE)[,-5]
Then I want to add some rows in the above data frame or matrix. It is fine for Australian data (e.g, AUSe[1,3]+AUSe[2,3]). But error occurred when same command is applied to Belgium data: Error in BELe[1, 3] + BELe[2, 3] : non-numeric argument to binary operator. But if you look at the text file, you know those are two numbers. It is clear that R treated a number as a character when reading the text file, which is rather odd.

Answer 1

Try this instead:
BELe<-read.table("BEL.Exposures_1x1.txt",skip=1, colClasses="numeric", header=TRUE)[,-5]
Or you could surely post just a tiny bit of that file and not violate any copyright laws at least in my jurisdiction (which I think is the same one as The Human Mortality Database).
Belgium, Exposure to risk (period 1x1) Last modified: 04-Feb-2011, MPv5 (May07)
Year Age Female Male Total
1841 0 61006.15 62948.23 123954.38
1841 1 55072.53 56064.21 111136.73
1841 2 51480.76 52521.70 104002.46
1841 3 48750.57 49506.71 98257.28
.... . ....
So I might have suggested the even more accurate colClasses:
BELe<-read.table("BEL.Exposures_1x1.txt",skip=2, # really two lines to skip I think
colClasses=c(rep("integer", 2), rep("numeric",3)),
header=TRUE)[,-5]
I suspect the promlem occurs because of lines like these:
1842 110+ 0.00 0.00 0.00
So you will need to determine how much interest you have in preserving the 110+ values. With my method they will be coerced to NA's. (Well I thought they would be but like you I got an error. So this multi-step process is needed:
BELe<-read.table("Exposures_1x1.txt",skip=2,
header=TRUE)
BELe[ , 2:5] <- lapply(BELe[ , 2:5], as.character)
str(BELe)
#-------------
'data.frame': 18759 obs. of 5 variables:
$ Year : int 1841 1841 1841 1841 1841 1841 1841 1841 1841 1841 ...
$ Age : chr "0" "1" "2" "3" ...
$ Female: chr "61006.15" "55072.53" "51480.76" "48750.57" ...
$ Male : chr "62948.23" "56064.21" "52521.70" "49506.71" ...
$ Total : chr "123954.38" "111136.73" "104002.46" "98257.28" ...
#-------------
BELe[ , 2:5] <- lapply(BELe[ , 2:5], as.numeric)
#----------
Warning messages:
1: In lapply(BELe[, 2:5], as.numeric) : NAs introduced by coercion
2: In lapply(BELe[, 2:5], as.numeric) : NAs introduced by coercion
3: In lapply(BELe[, 2:5], as.numeric) : NAs introduced by coercion
4: In lapply(BELe[, 2:5], as.numeric) : NAs introduced by coercion
str(BELe)
#-----------
'data.frame': 18759 obs. of 5 variables:
$ Year : int 1841 1841 1841 1841 1841 1841 1841 1841 1841 1841 ...
$ Age : num 0 1 2 3 4 5 6 7 8 9 ...
$ Female: num 61006 55073 51481 48751 47014 ...
$ Male : num 62948 56064 52522 49507 47862 ...
$ Total : num 123954 111137 104002 98257 94876 ...
# and just to show that tey are not really integers:
BELe$Total[1:5]
#[1] 123954.38 111136.73 104002.46 98257.28 94875.89

Answer 2

The way I typically read those files is:
BELexp <- read.table("BEL.Exposures_1x1.txt", skip = 2, header = TRUE, na.strings = ".", as.is = TRUE)
Note that Belgium lost 3 years of data in WWI that may never be recovered, and hence these three years are all NAs, which in those files are marked with ".", a character string. Hence the argument na.strings = ".". Specifying that argument will take care of all columns except Age, which is character (intentionally), due to the "110+". The reason the HMD does this is so that users have to be intentional about treatment of the open age group. You can convert the age column to integer using:
BELexp$Age <- as.integer(gsub("[+]", "", BELexp$Age))
Since such issues are long the bane of R-HMD users, the HMD has recently posted some R functions in a small but growing package on github called (for now) DemogBerkeley. The function readHMD() removes all of the above headaches:
library(devtools)
install_github("DemogBerkeley", subdir = "DemogBerkeley", username = "UCBdemography")
BELexp <- readHMD("BEL.Exposures_1x1.txt")
Note that a new indicator column, called OpenInterval is added, while Age is converted to integer as above.

Answer 3

Can you try read.csv(... stringsAsFactors=FALSE) ?