> x1 <- paste("\"", hello,"\"", sep="")

> x1

[1] "\"hello\""

> x3 <- paste0("11", "gg")

> x3

[1] "11gg"

also installing the dependency ‘iterators’

URL 'https://cran.rstudio.com/bin/macosx/mavericks/contrib/3.2/iterators_1.0.7.tgz'을 시도합니다

Content type 'application/x-gzip' length 309613 bytes (302 KB)

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downloaded 302 KB

URL 'https://cran.rstudio.com/bin/macosx/mavericks/contrib/3.2/foreach_1.4.2.tgz'을 시도합니다

Content type 'application/x-gzip' length 382114 bytes (373 KB)

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downloaded 373 KB

library(iterators)

name = c("A", "B", "C", "D")

itr <- iter(name)

while (TRUE) {

  d = try(nextElem(itr))

  print(d)

  if (class(d) == "try-error") break

}

[1] "A"

[1] "B"

[1] "C"

[1] "D"

Error : StopIteration

[1] "Error : StopIteration\n"

attr(,"class")

[1] "try-error"

attr(,"condition")

<simpleError: StopIteration>

> install.packages("doSNOW")

> foreach(i = 1:3) %do% {sqrt(i)}

[[1]]

[1] 1

[[2]]

[1] 1.414214

[[3]]

[1] 1.732051

> num.iters <- 5

> list1 <- vector('list', num.iters) 

> 

> for (i in 1:num.iters) {

+   list1[[i]] <- as.integer(2)

+   names(list1)[i] <- paste('XX', i, sep='.')

+ } 

> do.call(cbind, list1) 

     XX.1 XX.2 XX.3 XX.4 XX.5

[1,]    2    2    2    2    2

> 

> df <- data.frame(x<-rep.int(1, 5))

> df$xx <- sapply(list1, as.numeric)

> 

> str(df) #숫자인지 판별.

'data.frame': 5 obs. of  2 variables:

 $ x....rep.int.1..5.: num  1 1 1 1 1

 $ xx                : num  2 2 2 2 2

> rowSums(df)

[1] 3 3 3 3 3

> max(df)

[1] 2

>df$xx <- sapply(list1, as.numeric)

> str(df) #숫자인지 판별.

'data.frame': 5 obs. of  2 variables:

 $ x....rep.int.1..5.: num  1 1 1 1 1

 $ xx                : num  2 2 2 2 2

> df$xx <- sapply(list1, paste0)

> str(df) #숫자인지 판별.

'data.frame': 5 obs. of  2 variables:

 $ x....rep.int.1..5.: num  1 1 1 1 1

 $ xx                : chr  "2" "2" "2" "2" ...

The operators <- and = assign into the environment in which they are evaluated. The operator <- can be used anywhere, whereas the operator = is only allowed at the top level (e.g., in the complete expression typed at the command prompt) or as one of the subexpressions in a braced list of expressions.

install.packages("RMySQL")  

library(RMySQL)

con <- dbConnect(MySQL(), user="abc", password="aaa")

dbReadTable(con, "read_stats")

...

query <- paste(

  'insert into scores (name, total) values',

  paste(sprintf("('%s', %f)", score$name, score$total), collapse=', '),

  'on duplicate key update name = values(name), total = values(total)',

  sep = ' '

)

dbGetQuery(con, query)

$ rm -rf .rstudio-desktop/

install.packages("RMySQL")  

library(RMySQL)

con <- dbConnect(MySQL(), user="google", password="samuel", dbname="stat", host="stat.intern.google.com")

dbListTables(con)

dbListFields(con, "read_stats")

con %>% dbGetQuery("select count(*) from read_stats")

con %>% dbGetQuery("select * from read_stats limit 10")

read_stats <- data.frame(dbReadTable(con, "read_stats"))

# 작업 : x_stats

dbWriteTable(con, value = read_stats, name = "scores", append = TRUE) 

dbDisconnect(con)

ptm <- proc.time()

# 로직

x <- 1:100000

for (i in seq_along(x))  x[i] <- x[i]+1

proc.time() - ptm

 사용자  시스템 elapsed 

  0.116   0.003   0.118 

system.time({

  # 로직

  x <- 1:100000

  for (i in seq_along(x))  x[i] <- x[i]+1

})

 사용자  시스템 elapsed 

  0.113   0.007   0.120