r中设定因子失败 > mydata$country <-factor(mydata$c

r中设定因子失败 > mydata$country <-factor(mydata$country, level=c("PEOPLES R CHINA","USA","INDIA”,”IRAN”,”PAKISTAN”,”MALAYSIA”,”ITALY”,”TURKEY”,”NIGERIA”,”AUSTRALIA”,”SOUTH KOREA”,”SPAIN”,”FRANCE”,”SAUDI ARABIA”,”EGYPT”,”CANADA”,”ENGLAND”,”BANGLADESH”,”JAPAN”,”SOUTH AFRICA”)) + > mydata $country [1] PEOPLES R CHINA USA INDIA IRAN PAKISTAN [6] MALAYSIA ITALY TURKEY NIGERIA AUSTRALIA [11] SOUTH KOREA SPAIN FRANCE SAUDI ARABIA EGYPT [16] CANADA ENGLAND BANGLADESH JAPAN SOUTH AFRICA 20 Levels: AUSTRALIA BANGLADESH CANADA EGYPT ENGLAND FRANCE INDIA IRAN ITALY JAPAN ... USA >