R用read.csv读数据后出现levels，用read.csv("Netherlands'gdp.csv",stringsAsFactors=F)，数据变成字符型；再把字符型转换成数值型，就出来NANANA, 求大神解答， 要疯了> GDP
[1] "5,996"  "6,032"  "6,084"  "6,543"  "6,907"  "7,326"  "7,499"  "7,614"  "7,482"  "7,737"
[11] "8,287"  "8,202"  "8,639"  "8,832"  "9,437"  "9,798"  "9,936"  "10,341" "10,894" "11,462"
[21] "11,967" "12,319" "12,597" "13,081" "13,497" "13,374" "13,885" "14,177" "14,424" "14,647"
[31] "14,705" "14,525" "14,291" "14,483" "14,900" "15,283" "15,617" "15,737" "16,044" "16,695"
[41] "17,262" "17,548" "17,720" "17,824" "18,223" "18,697" "19,248" "19,973" "20,631" "21,457"
[51] "22,148" "22,411" "22,291" "22,267" "22,696" "23,114" "23,867" "24,756" "25,112"
> gdp<-as.numeric(GDP);gdp
Warning message:
NAs introduced by coercion
[1] NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA
[31] NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA
>