我运行了一些基准测试
library(dplyr)
library(data.table)
library(microbenchmark)
dt.data.frame.way <- function(data) data[X > 0 & Y > 0 & Z > 0]
dplyr.way <- function(df) filter(df, X > 0, Y > 0, Z > 0)
real.data.frame.way <- function(df) df[df$X > 0 & df$Y > 0 & df$Z > 0,]
data <- data.table(X=seq(-5,5,1), Y=seq(-5,5,1), Z=seq(-5,5,1))
setkey(data, X, Y, Z)
df <- as.data.frame(data)
microbenchmark(times = 10,
dt.data.frame.way(data),
dplyr.way(df),
real.data.frame.way(df))
# Unit: microseconds
# expr min lq mean median uq max neval
# dt.data.frame.way(data) 710.426 754.287 871.8784 824.7565 942.998 1180.458 10
# dplyr.way(df) 951.309 1045.246 12303.3462 1142.7440 1246.668 112775.934 10
# real.data.frame.way(df) 137.239 162.591 181.5254 187.9785 197.373 231.594 10
将示例数据简单克隆到 550 万行。
data <- data.table(X=seq(-5,5,1), Y=seq(-5,5,1), Z=seq(-5,5,1))
data <- rbindlist(lapply(1:5e5, function(i) data)) # 5500000 rows
setkey(data, X, Y, Z)
df <- as.data.frame(data)
microbenchmark(times = 10,
dt.data.frame.way(data),
dplyr.way(df),
real.data.frame.way(df))
# Unit: milliseconds
# expr min lq mean median uq max neval
# dt.data.frame.way(data) 656.2978 668.0560 730.9246 696.6560 831.0877 846.0517 10
# dplyr.way(df) 632.4096 639.1141 709.4308 678.9436 717.3018 1015.7663 10
# real.data.frame.way(df) 964.4298 1022.1772 1075.8448 1077.4437 1125.0037 1192.7410 10
该任务的性能似乎很难提高。通常它取决于数据。