I have the below data frame which contains infomation about different states. 

```
long=c(-106.61291,-106.61291,-106.61291,-81.97224,-81.97224,-81.97224,-84.4277,-84.4277,-84.4277)
lat=c(35.04333,35.04333,35.04333,33.37378,33.37378,33.37378,33.64073,33.64073,33.64073)
city=c("Albuquerque","Albuquerque","Albuquerque","Augusta","Augusta","Augusta","Atlanta","Atlanta","Atlanta")
date=c("2017-08-22","2017-08-23","2017-09-24","2017-09-28","2017-10-24","2017-09-22","2017-11-12","2017-010-14","2017-09-03")
value=c(12,10.8,18.3,12.4,43,21,12,32.1,14)

df<-data.frame(long,lat,city,date,value)

```

**Problem**:I want to write each city information in individual csv's. And each csv should look
like below.
Final output:

```
Albuquerque.csv
       long      lat        city       date value
1 -106.6129 35.04333 Albuquerque 2017-08-22  12.0
2 -106.6129 35.04333 Albuquerque 2017-08-23  10.8
3 -106.6129 35.04333 Albuquerque 2017-09-24  18.3

Augusta.csv
      long      lat    city       date value
1 -81.97224 33.37378 Augusta 2017-09-28  12.4
2 -81.97224 33.37378 Augusta 2017-10-24  43.0
3 -81.97224 33.37378 Augusta 2017-09-22  21.0

Atlanta.csv
      long      lat    city        date value
1 -84.4277 33.64073 Atlanta  2017-11-12  12.0
2 -84.4277 33.64073 Atlanta 2017-010-14  32.1
3 -84.4277 33.64073 Atlanta  2017-09-03  14.0

```

Thanks in advance!