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Change value of some column in xts based on other columns values with lookback

开发者 https://www.devze.com 2023-02-13 14:01 出处:网络
I have the following xts object (representing long/short entries (column 1 and 2) and exit (columns 3 and 4) triggerswith \"aggregate\" signal column which should be 1 (system is long), -1 (system is

I have the following xts object (representing long/short entries (column 1 and 2) and exit (columns 3 and 4) triggers with "aggregate" signal column which should be 1 (system is long), -1 (system is short) or 0 (system is flat). I can not make this work for "aggregate" signal column5...

The data:

         LongEntrySignal ShortEntrySignal LongExitSignal ShortExitSignal Signal
18.02.93               0                0              1               0      0
19.02.93               0                0              0               1      0
22.02.93               1                0              0               0      1
23.02.93               0                0              0               0      0
24.02.93               0                0              0               0      0
25.02.93               0                0              0               0      0
26.02.93               0                0              1               0      0
01.03.93               0                0              1               0      0
04.03.93               0                1              0               0     -1
05.03.93               0                0              0               0      0
11.03.93               0                0              0               1      0
12.03.93               0                0              1               0      0

I would like to transform the data in this form:

         LongEntrySignal ShortEntrySignal LongExitSignal ShortExitSignal Signal
18.02.93               0                0              1               0      0
19.02.93               0                0              0               1      0
22.02.93               1                0              0               0      1
23.02.93               0                0              0               0      1
24.02.93               0                0              0               0      1
25.02.93               0                0              0               0      1
26.02.93               0                0              1               0      1
01.03.93               0                0              1               0      0
04.03.93               0                1              0               0     -1
05.03.93               0                0              0               0     -1
11.03.93               0                0              0               1     -1
12.03.93               0                0              1               0      0

I tried uprogramming a function like below (but id does not work; the commented out part also does not work and is terribly slow - I am aware of using loops in R is slow but that was the only idea that I had):

padMinusPlusOnes<-function(signals, longEntryColumn=1, shortEntryColumn=2, signalsColumn=5) {   
    ret<-signals
#get all indexes between long entry equals 1 to long exit equals 1 and set signalsColumn for these rows to 1
    ret[(lag(ret)[, longEntryColumn] == 1) & (ret[, signalsColumn] == 0), signalsColumn]<-1
#get all indexes between short entry equals 1 to short exit equals 1 and set signalsColumn for these rows to -1
    开发者_StackOverflow社区ret[(lag(ret)[, shortEntryColumn] == -1) & (ret[, signalsColumn] == 0), signalsColumn]<--1

    return(ret)

#   ret<-signals
#   for (i in 2:NROW(ret)) {
#       if ((ret[i - 1, longEntryColumn] == 1) & (ret[, signalsColumn] == 0)) {
#           ret[i, signalsColumn]<-1
#       }
#       if ((ret[i - 1, shortEntryColumn] == -1) & (ret[, signalsColumn] == 0)) {
#           ret[i, signalsColumn]<--1
#       }
#   }
#   
#   return(ret)
}

Thanks for your kind help in how to transform the data.

Kind regards, Samo.

Edit note: After receving two very helpful and insightful answers from Prasad Chalasani and J. Winchester I realized I left out important information from how my data is structured. So I changed the data above to better reflect my data and copied original (based on which two answers were based) below:

The data:

         LongEntrySignal ShortEntrySignal LongExitSignal ShortExitSignal Signal
18.02.93               0                0              0               0      0
19.02.93               0                0              0               0      0
22.02.93               1                0              0               0      1
23.02.93               0                0              0               0      0
24.02.93               0                0              0               0      0
25.02.93               0                0              0               0      0
26.02.93               0                0              1               0      0
01.03.93               0                0              0               0      0
04.03.93               0                1              0               0     -1
05.03.93               0                0              0               0      0
11.03.93               0                0              0               1      0
12.03.93               0                0              0               0      0

I would like to transform the data in this form:

         LongEntrySignal ShortEntrySignal LongExitSignal ShortExitSignal Signal
18.02.93               0                0              0               0      0
19.02.93               0                0              0               0      0
22.02.93               1                0              0               0      1
23.02.93               0                0              0               0      1
24.02.93               0                0              0               0      1
25.02.93               0                0              0               0      1
26.02.93               0                0              1               0      1
01.03.93               0                0              0               0      0
04.03.93               0                1              0               0     -1
05.03.93               0                0              0               0     -1
11.03.93               0                0              0               1     -1
12.03.93               0                0              0               0      0


You don't need to use loops, nor do you need to "lookback". You can use the vectorized function cumsum to get what you want. Assuming your long entry/exit and short entry/exit periods are non-overlapping, you can do this: First make up dummy signals:

n <- 15
zeros <- rep(0,n)
LongEnt <- replace(zeros, c(1, 12), 1)
LongEx <- replace(zeros, c(4, 14), 1)
ShortEnt <- replace(zeros, 6, 1)
ShortEx <- replace(zeros, 10, 1)

Now do some cumsum magic to get the right "aggregate" signal column:

SigLong <- cumsum(LongEnt) - cumsum(LongEx) + LongEx
SigShort <- -cumsum(ShortEnt) + cumsum(ShortEx) - ShortEx
> cbind(LongEnt, LongEx, ShortEnt, ShortEx, Signal = SigLong + SigShort)
      LongEnt LongEx ShortEnt ShortEx Signal
 [1,]       1      0        0       0      1
 [2,]       0      0        0       0      1
 [3,]       0      0        0       0      1
 [4,]       0      1        0       0      1
 [5,]       0      0        0       0      0
 [6,]       0      0        1       0     -1
 [7,]       0      0        0       0     -1
 [8,]       0      0        0       0     -1
 [9,]       0      0        0       0     -1
[10,]       0      0        0       1     -1
[11,]       0      0        0       0      0
[12,]       1      0        0       0      1
[13,]       0      0        0       0      1
[14,]       0      1        0       0      1
[15,]       0      0        0       0      0

Update. According to the OP's modified question, we need to handle the case of arbitrary sequence of entry/exit signals, and find the periods between the first entry and the corresponding first exit. Here's a way to do this with very simple arihtmetic operations (i.e. no expensive lookbacks or if/else checking). We just need a small modification of the cumsum function that I will call cumplus -- this is like cumsum, except that after taking each sum, it replaces it with 1 or 0 depending on whether it's positive or not:

cumplus <- function(y) Reduce(function(a,b) a + b > 0, y, 0, accum=TRUE)[-1]

(Incidentally, Reduce is a nice way to compactly define a cumulative function without explicitly writing out the for loop -- see ?Reduce for details).

Now take an example of Entry/exit signals:

LongEnt <- c(1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 
0, 1, 0, 0)
LongEx <- c(0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 
1, 0, 0, 1)

x <- LongEnt - LongEx  
z <- cumplus(x)

This is almost what we want... we just need to insert the 1s at the end of each ones-block.

z <- z - c(0,pmin(0,diff(z)))

> cbind(LongEnt, LongEx, signal = z)
      LongEnt LongEx signal
 [1,]       1      0      1
 [2,]       0      0      1
 [3,]       0      0      1
 [4,]       1      0      1
 [5,]       0      0      1
 [6,]       0      0      1
 [7,]       1      0      1
 [8,]       0      0      1
 [9,]       0      1      1
[10,]       0      0      0
[11,]       0      0      0
[12,]       0      1      0
[13,]       1      0      1
[14,]       0      0      1
[15,]       0      0      1
[16,]       1      0      1
[17,]       0      0      1
[18,]       0      0      1
[19,]       0      1      1
[20,]       0      0      0
[21,]       0      1      0
[22,]       1      0      1
[23,]       0      0      1
[24,]       0      1      1

Dealing with the short entry/exits would of course be similar.


I have made a couple logical assumptions, namely: the system starts in neutral state (ie zero); if the system leaves "zero state" by an "entry" signal of either type (long/short), the next signal must be an "exit" signal of the same type. If I read your data into a matrix named sigmat I can do the following.

streamLong <- with(sigmat, LongEntrySignal == 1 | LongExitSignal == 1)
switches <- which(streamLong)
mat <- cbind(c(1, switches), c(switches, length(streamLong) + 1), 0:1)
stateLong <- do.call("c", apply(mat, 1, function(ro)rep(ro[3], ro[2] - ro[1])))

streamShort <- with(sigmat, ShortEntrySignal == 1 | ShortExitSignal == 1)
switches <- which(streamShort)
mat <- cbind(c(1, switches), c(switches, length(streamShort) + 1), 0:1)
stateShort <- do.call("c", apply(mat, 1, function(ro)rep(ro[3], ro[2] - ro[1])))

# EDIT: The entry signal stays "on" until end of the exit day 
# so add one to the on sequences, and subtract one from the off sequences
sigRLE <- rle(stateLong - stateShort)
sigRLE$lengths[-1] <- sigRLE$lengths[-1] + 1:0 + 0:-1
sigmat$signal <- rep(sigRLE$values, sigRLE$lengths)

Here is the output.

R> sigmat
       date LongEntrySignal ShortEntrySignal LongExitSignal ShortExitSignal Signal signal
1  18.02.93               0                0              0               0      0      0
2  19.02.93               0                0              0               0      0      0
3  22.02.93               1                0              0               0      1      1
4  23.02.93               0                0              0               0      0      1
5  24.02.93               0                0              0               0      0      1
6  25.02.93               0                0              0               0      0      1
7  26.02.93               0                0              1               0      0      1
8  01.03.93               0                0              0               0      0      0
9  04.03.93               0                1              0               0     -1     -1
10 05.03.93               0                0              0               0      0     -1
11 11.03.93               0                0              0               1      0     -1
12 12.03.93               0                0              0               0      0      0


I'm sure there's a "magical" (ie vectorized) way to do this, but for now, here's a workable loop solution.

# your example data
sigmat <- structure(list(
  date = structure(c(6L, 7L, 8L, 9L, 10L, 11L, 12L, 1L, 2L, 3L, 4L, 5L), 
  .Label = c("01.03.93", "04.03.93", "05.03.93", "11.03.93", "12.03.93", 
    "18.02.93", "19.02.93", "22.02.93", "23.02.93", "24.02.93", 
    "25.02.93", "26.02.93"), class = "factor"), 
  LongEntrySignal = c(0L, 0L, 1L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L), 
  ShortEntrySignal = c(0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 1L, 0L, 0L, 0L), 
  LongExitSignal = c(1L, 0L, 0L, 0L, 0L, 0L, 1L, 1L, 0L, 0L, 0L, 1L), 
  ShortExitSignal = c(0L, 1L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 1L, 0L), 
  Signal = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)), 
  .Names = c("date", "LongEntrySignal", "ShortEntrySignal", 
    "LongExitSignal", "ShortExitSignal", "Signal"), 
  row.names = c(NA, -12L), class = "data.frame")

# if there is an entry/exit signal, turn on/off
# otherwise keep the same state as the day before
sigShort <- sigmat$ShortEntrySignal - sigmat$ShortExitSignal
sigLong  <- sigmat$LongEntrySignal -  sigmat$LongExitSignal
for(i in 2:nrow(sigmat)) {
  if(sigShort[i] == 0) sigShort[i] <- sigShort[i-1]
  if(sigLong[i]  == 0) sigLong[i]  <- sigLong[i-1]
}

# The entry signal stays "on" until end of the exit day 
# so extend the on sequences by one day, and shorten the off sequences
sigRLE <- rle((sigLong > 0) * 1 - (sigShort > 0) * 1)
sigRLE$lengths[-1] <- sigRLE$lengths[-1] + 1:0 + 0:-1
sigmat$Signal <- rep(sigRLE$values, sigRLE$lengths)
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