R CheatSheet

1. Google Map

 

#reference:https://rpubs.com/Japhilko82/ggmap

FinalMap<-qmap("Australia",zoom=4)

library(RODBC)
dbhandle <- odbcDriverConnect('driver={SQL Server};server=xxx;database=xxx;trusted_connection=true')
data_hrchy <- sqlQuery(dbhandle, 'select * from xxx')
data_company<-unique(data_hrchy[,"Company Name"])

summary(data_company)

library(ggmap)
place<-as.character(data_company)
positions<-geocode(place)
positions

locationt <- geocode("Australia")

mapImageData1 <- get_map(location = locationt,
color = "color",
source = "google",
maptype = "satellite",
zoom = 4)

output_graph<-ggmap(mapImageData1,
extent = "device",
ylab = "Latitude",
xlab = "Longitude")

output_graph + geom_point(data=positions, aes(x=lon, y=lat), color=rgb(1,0.1,0.1), size=5, alpha=0.5)

 

2.SQL SERVER

library(RODBC)
dbhandle <- odbcDriverConnect('driver={SQL Server};server=SQLAU101MEL0240.GLOBALTEST.ANZ.COM,49168;database=CVA2_FrontEnd;trusted_connection=true')
r <- sqlQuery(dbhandle, 'select * from dbo.BRKR_HRCHY')

 

3. each row in a set

for (i in 1:nrow(points)) {
print(points[i,])
}

 

4. data type

typeof

 

5. remove column

train_data.pick$Fare = NULL  

 

6.check null

summary(train_data$Age)

 

7. recall memory

gc()

 

8. add item to vector

v = NULL
for ( i in 1:nrow(train_data.pick)) {
#print(train_data.pick$Sex[i])
if(train_data.pick$Sex[i]=='male'){
v <- c(v,1)
}
else{
v <- c(v,2)
}
}

 

9. ignore null

 na.omit()

 

10. trim

gdata

 

11. get letters from string

gsub("pattern","rep",t)

pattern: regular expression

replace substring matching 'pattern' in t with 'rep'

 

12.char to code

intToUtf8(65)
utf8ToInt("A")

 

13.