exercise1

dta <- read.table("/Users/Tjlee/Desktop/weather/student2017.txt", header = T)
dta

##           ID
## 1  D84057058
## 2  C44035023
## 3  D84041162
## 4  D84046081
## 5  D84021057
## 6  U36037025
## 7  U36041074
## 8  U36041090
## 9  U36051087
## 10 U36031118
## 11 U36041082
## 12 U76051019
## 13 U76054025
## 14 U76064062
## 15 U76041064
## 16 U76041080

fix(dta)

## Warning in edit.data.frame(get(subx, envir = parent), title = subx, ...): added
## factor levels in 'ID'

dta

##           ID
## 1  D84057058
## 2  C44035023
## 3  D84041162
## 4  D84046081
## 5  D84021057
## 6  U36037025
## 7  U36041074
## 8  U36041090
## 9  U36051087
## 10 U36031118
## 11 U36041082
## 12 U76051019
## 13 U76054025
## 14 U76064062
## 15 U76067010
## 16 U76041064
## 17 U76041080