I want to use the plyrmr package while keeping my existent code written in dplyr and thus I want to use the "magic.wand" function. I am using the "mtcars" dataset for simplicity and the the path to it is "/user/sgerony/mtcars2" on the HDFS (Hadoop Distributed File System).
The block of code contains base functions but also dplyr functions and this is my code:
magic.wand(rename,TRUE)
filename <- "/user/sgerony/mtcars"
complex.function = function(x){
x$carb <- x[,ncol(x)]*2
x$carb <- x$carb+2
x <- as.data.frame(rename(x, lol=carb))
return(x)
}
magic.wand(complex.function)
# does NOT work
input(filename) %|% complex.function()
Result (Note: Row names have dissapeared)
mpg cyl disp hp drat wt qsec vs am gear lol
1 21.0 6 160.0 110 3.90 2.620 16.46 0 1 4 10
2 21.0 6 160.0 110 3.90 2.875 17.02 0 1 4 10
3 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 4
4 21.4 6 258.0 110 3.08 3.215 19.44 1 0 3 4
5 18.7 8 360.0 175 3.15 3.440 17.02 0 0 3 6
6 18.1 6 225.0 105 2.76 3.460 20.22 1 0 3 4
7 14.3 8 360.0 245 3.21 3.570 15.84 0 0 3 10
8 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 6
9 22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 6
10 19.2 6 167.6 123 3.92 3.440 18.30 1 0 4 10
11 17.8 6 167.6 123 3.92 3.440 18.90 1 0 4 10
12 16.4 8 275.8 180 3.07 4.070 17.40 0 0 3 8
13 17.3 8 275.8 180 3.07 3.730 17.60 0 0 3 8
14 15.2 8 275.8 180 3.07 3.780 18.00 0 0 3 8
15 10.4 8 472.0 205 2.93 5.250 17.98 0 0 3 10
16 10.4 8 460.0 215 3.00 5.424 17.82 0 0 3 10
17 14.7 8 440.0 230 3.23 5.345 17.42 0 0 3 10
18 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 4
19 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 6
20 33.9 4 71.1 65 4.22 1.835 19.90 1 1 4 4
21 21.5 4 120.1 97 3.70 2.465 20.01 1 0 3 4
22 15.5 8 318.0 150 2.76 3.520 16.87 0 0 3 6
23 15.2 8 304.0 150 3.15 3.435 17.30 0 0 3 6
24 13.3 8 350.0 245 3.73 3.840 15.41 0 0 3 10
25 19.2 8 400.0 175 3.08 3.845 17.05 0 0 3 6
26 27.3 4 79.0 66 4.08 1.935 18.90 1 1 4 4
27 26.0 4 120.3 91 4.43 2.140 16.70 0 1 5 6
28 30.4 4 95.1 113 3.77 1.513 16.90 1 1 5 6
29 15.8 8 351.0 264 4.22 3.170 14.50 0 1 5 10
30 19.7 6 145.0 175 3.62 2.770 15.50 0 1 5 14
31 15.0 8 301.0 335 3.54 3.570 14.60 0 1 5 18
32 21.4 4 121.0 109 4.11 2.780 18.60 1 1 4 6
Question 1: Is this the right way to do? meaning do I have to call a first time the magic.wand for the dplyr functions and then for the bloc of code?
Question 2: Why can't I call the magic.wand function like this?
magic.wand(dplyr::rename,TRUE)
Result:
> magic.wand(dplyr::rename,TRUE)
Error in match.fun(paste0(f.name, "_")) :
'paste0(c("::", "dplyr", "rename"), "_")' is not a function, character or symbol
Details: It creates functions of names "::","::.data.frame","::.default","plyr","rename"
Isn't it necessary to be sure that we are not using functions contained in several libraries?
Question 3: Why do I have to put "TRUE" as a second argument of the first magic.wand call and not the last one?
filename<-"/user/sgerony/mtcars"
magic.wand(rename,TRUE)
filename <- "/user/sgerony/mtcars"
complex.function = function(x){
x$carb <- x[,ncol(x)]*2
x$carb <- x$carb+2
x <- as.data.frame(rename(x, lol=carb))
return(x)
}
magic.wand(complex.function,TRUE)
Error:
Error in get(as.character(FUN), mode = "function", envir = envir) :
object 'complex.function_' of mode 'function' was not found
Question 4: What if my block of code is using the dplyr piping operator? namely:
complex.function = function(x){
x$carb <- x[,ncol(x)]*2
x$carb <- x$carb+2
x <- as.data.frame(x %>% rename(lol=carb))
return(x)
}
Should I just replace the "%>%" by the plyrmr piping operator? Namely "%|%"?
Question 5: Should I call the magic.wand function on dplyr functions that are equivalent to plyrmr functions like "group_by"?
Question 6: Why do I have an error when using as.POSIXct?
magic.wand(mutate,TRUE)
filename <- "/user/sgerony/mtcars"
complex.function = function(x){
x$carb <- x[,ncol(x)]*2
x$carb <- x$carb+2
x <- as.data.frame(mutate(x,date.time=as.POSIXct("2014-01-01 03:15")))
return(x)
}
magic.wand(complex.function)
#Works
mtcars %|% complex.function()
# does NOT work
input(filename) %|% complex.function()
I realize this is a big question, so thanks for trying to help