问题
I have a column containing speed measurements which I need to change to numeric so that I can use both the mean and sum functions. However, when I do convert them the values change substantially.
Why is this?
This is what my data look like at first:
And here is the structure of the data frame:
'data.frame': 1899571 obs. of 20 variables:
$ pcd : Factor w/ 1736958 levels "AB101AA","AB101AB",..: 1 2 3 4 5 6 6 7 7 8
$ pcdstatus : Factor w/ 5 levels "Insufficient Data",..: 4 4 4 4 4 2 3 2 3 3 ...
$ mbps2 : Factor w/ 3 levels "N","N/A","Y": 2 2 2 2 2 2 2 2 2 2 ...
$ averagesp : Factor w/ 301 levels ">=30","0","0.2",..: 301 301 301 301 301 301 301
$ mediansp : Factor w/ 302 levels ">=30","0","0.1",..: 302 302 302 302 302 302 302
$ maxsp : Factor w/ 301 levels ">=30","0","0.2",..: 301 301 301 301 301 301 301
$ nga : Factor w/ 2 levels "N","Y": 1 2 1 1 1 1 1 2 2 2 ...
$ connections: Factor w/ 119 levels "<3","0","1","10",..: 2 2 2 2 2 1 2 1 2 2 ...
$ pcd2 : Factor w/ 1736958 levels "AB10 1AA","AB10 1AB",..: 1 2 3 4 5 6 6 7 7 8
$ pcds : Factor w/ 1736958 levels "AB10 1AA","AB10 1AB",..: 1 2 3 4 5 6 6 7 7 8
$ oslaua : Factor w/ 407 levels "","95A","95B",..: 374 374 374 374 374 374 374
$ x : int 394251 394232 394181 394251 394371 394181 394181 394331 394331
$ y : int 806376 806470 806429 806376 806359 806429 806429 806530 806530
$ ctry : Factor w/ 4 levels "E92000001","N92000002",..: 3 3 3 3 3 3 3 3 3 3 ...
$ hro2 : Factor w/ 13 levels "","E12000001",..: 12 12 12 12 12 12 12 12 12 12
$ soa1 : Factor w/ 34381 levels "","E01000001",..: 32485 32485 32485 32485
$ dzone1 : Factor w/ 6507 levels "","E99999999",..: 128 128 128 128 112 128 128
$ soa2 : Factor w/ 7197 levels "","E02000001",..: 6784 6784 6784 6784 6784 6784
$ urindew : int 9 9 9 9 9 9 9 9 9 9 ...
$ soa1ni : Factor w/ 892 levels "","95AA01S1",..: 892 892 892 892 892 892 892 892
This is the code for converting my variables to numeric variables.
#convert individual columns to numeric variables
total$averagesp <- as.numeric(total$averagesp)
total$mediansp <- as.numeric(total$mediansp)
total$maxsp <- as.numeric(total$maxsp)
total$mbps2 <- as.numeric(total$mbps2)
total$nga <- as.numeric(total$nga)
total$connections <- as.numeric(total$connections)
But I have this strange output afterwards where all my data have been inflated:
Any help would be much appreciated - thank you!
回答1:
See FAQ 7.10. Basically when you use as.numeric on a factor then you get the underlying integers. The FAQ has the recipes for turning them into the numbers represented by the strings.
来源：https://stackoverflow.com/questions/22790529/the-as-numeric-function-changes-the-values-in-my-dataframe