[1,drop=TRUE] no longer returns vector from FLQuant.

[colinpmillar]

Change in behaviour occurs in commit: 6704455

Starting with a simple 2D quant:

    library(FLCore)
    ## FLCore (Version 2.6.3.9005, packaged: Sat Sep 30 02:06:33 2017)

    (x <- FLQuant(as.numeric(paste0(rep(1:2, 9), 
                                    rep(1:9, each = 2))), dim = c(2, 9)))
    ## An object of class "FLQuant"
    ## , , unit = unique, season = all, area = unique
    ## 
    ##      year
    ## quant 1  2  3  4  5  6  7  8  9 
    ##     1 11 12 13 14 15 16 17 18 19
    ##     2 21 22 23 24 25 26 27 28 29
    ## 
    ## units:  NA

commit: 26fc70c

    install_github("flr/flcore@26fc70ceceb1608a44440c8f4688e822fe8e731d")
    ## Reloading installed FLCore
    ## FLCore (Version 2.6.3.9005, packaged: Sat Sep 30 02:07:00 2017)

    # up till now the following are and have been equivalent
    x@.Data[1:2,,,,,, drop=TRUE]
    ##      year
    ## quant  1  2  3  4  5  6  7  8  9
    ##     1 11 12 13 14 15 16 17 18 19
    ##     2 21 22 23 24 25 26 27 28 29

    x[1:2,,,,,, drop=TRUE]
    ##      year
    ## quant  1  2  3  4  5  6  7  8  9
    ##     1 11 12 13 14 15 16 17 18 19
    ##     2 21 22 23 24 25 26 27 28 29

    x[1:2, drop=TRUE]
    ##      year
    ## quant  1  2  3  4  5  6  7  8  9
    ##     1 11 12 13 14 15 16 17 18 19
    ##     2 21 22 23 24 25 26 27 28 29

following commit: 6704455

    install_github("flr/flcore@6704455aa29390c834310572c165025341be3231")
    ## Reloading installed FLCore
    ## FLCore (Version 2.6.3.9005, packaged: Sat Sep 30 02:07:25 2017)

    # after this commit the following are no longer equivalent
    x@.Data[1:2,,,,,, drop=TRUE]
    ##      year
    ## quant  1  2  3  4  5  6  7  8  9
    ##     1 11 12 13 14 15 16 17 18 19
    ##     2 21 22 23 24 25 26 27 28 29

    x[1:2,,,,,, drop=TRUE]
    ## [1] 11 21

    x[1:2, drop=TRUE]
    ## [1] 11 21

[iagomosqueira]

I see where the problem comes from. From that commit if a single vector of is given, and drop=TRUE, it is taken to be used to select elements along the whole object, for example

x[c(1,4,7,8), drop=TRUE]
[1] 11 22 14 24

The code doing it is at, https://github.com/flr/FLCore/blob/master/R/FLArray.R#L159

This is trying to mimic the behaviour of the array class, where you an do

x@.Data[c(1,2,4,5)]
[1] 11 21 22 13

which could not be done in FLQuant.

The confusion only occurs when sub-setting on the first dimension, not on others

x[,1:2, drop=TRUE]
     year
quant  1  2
    1 11 12
    2 21 22

Now, I would like to preserve this new behaviour, as it got added because it was needed, but would also like to find a way for your subsetting needs to work.

Are you trying to select some rows and also convert to an array with less dimensions?

[colinpmillar]

I was actually using what ever worked, so probably not a bug at all :)
The behaviour you have now, is what you get with array, so I am quite happy with that - it was more to make you aware that there was a change is how the [] function behaved.
Happy for this to be closed as an isssue

[iagomosqueira]

OK, if you find it too difficult to extract elements from an FLQuant into a plain array let me know and we look at it again