DF = data.frame(A=1:3, B=c("foo","A,Name","baz"))
fwrite(DF)
write.csv(DF, row.names=FALSE, quote=FALSE) # same
fwrite(DF, row.names=TRUE, quote=TRUE)
write.csv(DF) # same
DF = data.frame(A=c(2.1,-1.234e-307,pi), B=c("foo","A,Name","bar"))
fwrite(DF, quote='auto') # Just DF[2,2] is auto quoted
write.csv(DF, row.names=FALSE) # same numeric formatting
DT = data.table(A=c(2,5.6,-3),B=list(1:3,c("foo","A,Name","bar"),round(pi*1:3,2)))
fwrite(DT)
fwrite(DT, sep="|", sep2=c("{",",","}"))
if (FALSE) {
set.seed(1)
DT = as.data.table( lapply(1:10, sample,
x=as.numeric(1:5e7), size=5e6)) # 382MB
system.time(fwrite(DT, "/dev/shm/tmp1.csv")) # 0.8s
system.time(write.csv(DT, "/dev/shm/tmp2.csv", # 60.6s
quote=FALSE, row.names=FALSE))
system("diff /dev/shm/tmp1.csv /dev/shm/tmp2.csv") # identical
set.seed(1)
N = 1e7
DT = data.table(
str1=sample(sprintf("%010d",sample(N,1e5,replace=TRUE)), N, replace=TRUE),
str2=sample(sprintf("%09d",sample(N,1e5,replace=TRUE)), N, replace=TRUE),
str3=sample(sapply(sample(2:30, 100, TRUE), function(n)
paste0(sample(LETTERS, n, TRUE), collapse="")), N, TRUE),
str4=sprintf("%05d",sample(sample(1e5,50),N,TRUE)),
num1=sample(round(rnorm(1e6,mean=6.5,sd=15),2), N, replace=TRUE),
num2=sample(round(rnorm(1e6,mean=6.5,sd=15),10), N, replace=TRUE),
str5=sample(c("Y","N"),N,TRUE),
str6=sample(c("M","F"),N,TRUE),
int1=sample(ceiling(rexp(1e6)), N, replace=TRUE),
int2=sample(N,N,replace=TRUE)-N/2
) # 774MB
system.time(fwrite(DT,"/dev/shm/tmp1.csv")) # 1.1s
system.time(write.csv(DT,"/dev/shm/tmp2.csv", # 63.2s
row.names=FALSE, quote=FALSE))
system("diff /dev/shm/tmp1.csv /dev/shm/tmp2.csv") # identical
unlink("/dev/shm/tmp1.csv")
unlink("/dev/shm/tmp2.csv")
}
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