Contents

1 Motivation

The chihaya package saves DelayedArray objects for efficient, portable and stable reproduction of delayed operations in a new R session or other programming frameworks.

Check out the specification for more details.

2 Quick start

Make a DelayedArray object with some operations:

library(DelayedArray)
x <- DelayedArray(matrix(runif(1000), ncol=10))
x <- x[11:15,] / runif(5) 
x <- log2(x + 1)
x
## <5 x 10> DelayedMatrix object of type "double":
##           [,1]      [,2]      [,3] ...      [,9]     [,10]
## [1,] 0.1355403 0.9838739 0.6220638   . 0.9007200 0.3965987
## [2,] 2.4151064 1.7080830 3.2362302   . 3.0009334 3.1500356
## [3,] 1.3574752 1.8956751 1.3979611   . 2.4574956 1.4338160
## [4,] 0.8328421 0.5675563 0.9612706   . 0.9207816 0.5289011
## [5,] 3.0663418 3.3649236 2.8556433   . 3.3455338 2.6294542
showtree(x)
## 5x10 double: DelayedMatrix object
## └─ 5x10 double: Stack of 2 unary iso op(s)
##    └─ 5x10 double: Unary iso op with args
##       └─ 5x10 double: Subset
##          └─ 100x10 double: [seed] matrix object

Save it into a HDF5 file with saveDelayed():

library(chihaya)
tmp <- tempfile(fileext=".h5")
saveDelayed(x, tmp)
rhdf5::h5ls(tmp)
##                            group    name       otype  dclass      dim
## 0                              / delayed   H5I_GROUP                 
## 1                       /delayed    base H5I_DATASET   FLOAT    ( 0 )
## 2                       /delayed  method H5I_DATASET  STRING    ( 0 )
## 3                       /delayed    seed   H5I_GROUP                 
## 4                  /delayed/seed  method H5I_DATASET  STRING    ( 0 )
## 5                  /delayed/seed    seed   H5I_GROUP                 
## 6             /delayed/seed/seed   along H5I_DATASET INTEGER    ( 0 )
## 7             /delayed/seed/seed  method H5I_DATASET  STRING    ( 0 )
## 8             /delayed/seed/seed    seed   H5I_GROUP                 
## 9        /delayed/seed/seed/seed   index   H5I_GROUP                 
## 10 /delayed/seed/seed/seed/index       0 H5I_DATASET INTEGER        5
## 11       /delayed/seed/seed/seed    seed   H5I_GROUP                 
## 12  /delayed/seed/seed/seed/seed    data H5I_DATASET   FLOAT 100 x 10
## 13  /delayed/seed/seed/seed/seed  native H5I_DATASET INTEGER    ( 0 )
## 14            /delayed/seed/seed    side H5I_DATASET  STRING    ( 0 )
## 15            /delayed/seed/seed   value H5I_DATASET   FLOAT        5
## 16                 /delayed/seed    side H5I_DATASET  STRING    ( 0 )
## 17                 /delayed/seed   value H5I_DATASET   FLOAT    ( 0 )

And then load it back in later:

y <- loadDelayed(tmp)
y
## <5 x 10> DelayedMatrix object of type "double":
##           [,1]      [,2]      [,3] ...      [,9]     [,10]
## [1,] 0.1355403 0.9838739 0.6220638   . 0.9007200 0.3965987
## [2,] 2.4151064 1.7080830 3.2362302   . 3.0009334 3.1500356
## [3,] 1.3574752 1.8956751 1.3979611   . 2.4574956 1.4338160
## [4,] 0.8328421 0.5675563 0.9612706   . 0.9207816 0.5289011
## [5,] 3.0663418 3.3649236 2.8556433   . 3.3455338 2.6294542

Of course, this is not a particularly interesting case as we end up saving the original array inside our HDF5 file anyway. The real fun begins when you have some more interesting seeds.

3 More interesting seeds

We can use the delayed nature of the operations to avoid breaking sparsity. For example:

library(Matrix)
x <- rsparsematrix(1000, 1000, density=0.01)
x <- DelayedArray(x) + runif(1000)

tmp <- tempfile(fileext=".h5")
saveDelayed(x, tmp)
rhdf5::h5ls(tmp)
##            group     name       otype  dclass   dim
## 0              /  delayed   H5I_GROUP              
## 1       /delayed    along H5I_DATASET INTEGER ( 0 )
## 2       /delayed   method H5I_DATASET  STRING ( 0 )
## 3       /delayed     seed   H5I_GROUP              
## 4  /delayed/seed     data H5I_DATASET   FLOAT 10000
## 5  /delayed/seed dimnames   H5I_GROUP              
## 6  /delayed/seed  indices H5I_DATASET INTEGER 10000
## 7  /delayed/seed   indptr H5I_DATASET INTEGER  1001
## 8  /delayed/seed    shape H5I_DATASET INTEGER     2
## 9       /delayed     side H5I_DATASET  STRING ( 0 )
## 10      /delayed    value H5I_DATASET   FLOAT  1000
file.info(tmp)[["size"]]
## [1] 101912
# Compared to a dense array.
tmp2 <- tempfile(fileext=".h5")
out <- HDF5Array::writeHDF5Array(x, tmp2, "data")
file.info(tmp2)[["size"]]
## [1] 280271
# Loading it back in.
y <- loadDelayed(tmp)
showtree(y)
## 1000x1000 double: DelayedMatrix object
## └─ 1000x1000 double: Unary iso op with args
##    └─ 1000x1000 double, sparse: [seed] dgCMatrix object

We can also store references to external files, thus avoiding data duplication:

library(HDF5Array)
test <- HDF5Array(tmp2, "data")
stuff <- log2(test + 1)
stuff
## <1000 x 1000> DelayedMatrix object of type "double":
##              [,1]      [,2]      [,3] ...    [,999]   [,1000]
##    [1,] 0.4320952 0.4320952 0.4320952   . 0.4320952 0.4320952
##    [2,] 0.7223116 0.7223116 0.7223116   . 0.7223116 0.7223116
##    [3,] 0.1847288 0.1847288 0.1847288   . 0.1847288 0.1847288
##    [4,] 0.5732831 0.5732831 0.5732831   . 0.5732831 0.5732831
##    [5,] 0.2798067 0.2798067 0.2798067   . 0.2798067 0.2798067
##     ...         .         .         .   .         .         .
##  [996,] 0.6916716 0.6916716 0.6916716   . 0.6916716 0.6916716
##  [997,] 0.8858391 0.8858391 0.8858391   . 0.8858391 0.8858391
##  [998,] 0.7441049 0.7441049 0.7441049   . 0.7441049 0.7441049
##  [999,] 0.5522755 0.5522755 0.5522755   . 0.5522755 0.5522755
## [1000,] 0.9185483 0.9185483 1.5802479   . 0.9185483 0.9185483
tmp <- tempfile(fileext=".h5")
saveDelayed(stuff, tmp)
rhdf5::h5ls(tmp)
##                 group       name       otype  dclass   dim
## 0                   /    delayed   H5I_GROUP              
## 1            /delayed       base H5I_DATASET   FLOAT ( 0 )
## 2            /delayed     method H5I_DATASET  STRING ( 0 )
## 3            /delayed       seed   H5I_GROUP              
## 4       /delayed/seed     method H5I_DATASET  STRING ( 0 )
## 5       /delayed/seed       seed   H5I_GROUP              
## 6  /delayed/seed/seed dimensions H5I_DATASET INTEGER     2
## 7  /delayed/seed/seed       file H5I_DATASET  STRING ( 0 )
## 8  /delayed/seed/seed       name H5I_DATASET  STRING ( 0 )
## 9  /delayed/seed/seed     sparse H5I_DATASET INTEGER ( 0 )
## 10 /delayed/seed/seed       type H5I_DATASET  STRING ( 0 )
## 11      /delayed/seed       side H5I_DATASET  STRING ( 0 )
## 12      /delayed/seed      value H5I_DATASET   FLOAT ( 0 )
file.info(tmp)[["size"]] # size of the delayed operations + pointer to the actual file
## [1] 49642
y <- loadDelayed(tmp)
y
## <1000 x 1000> DelayedMatrix object of type "double":
##              [,1]      [,2]      [,3] ...    [,999]   [,1000]
##    [1,] 0.4320952 0.4320952 0.4320952   . 0.4320952 0.4320952
##    [2,] 0.7223116 0.7223116 0.7223116   . 0.7223116 0.7223116
##    [3,] 0.1847288 0.1847288 0.1847288   . 0.1847288 0.1847288
##    [4,] 0.5732831 0.5732831 0.5732831   . 0.5732831 0.5732831
##    [5,] 0.2798067 0.2798067 0.2798067   . 0.2798067 0.2798067
##     ...         .         .         .   .         .         .
##  [996,] 0.6916716 0.6916716 0.6916716   . 0.6916716 0.6916716
##  [997,] 0.8858391 0.8858391 0.8858391   . 0.8858391 0.8858391
##  [998,] 0.7441049 0.7441049 0.7441049   . 0.7441049 0.7441049
##  [999,] 0.5522755 0.5522755 0.5522755   . 0.5522755 0.5522755
## [1000,] 0.9185483 0.9185483 1.5802479   . 0.9185483 0.9185483

Session information

sessionInfo()
## R version 4.5.1 Patched (2025-09-10 r88807)
## Platform: x86_64-apple-darwin20
## Running under: macOS Monterey 12.7.6
## 
## Matrix products: default
## BLAS:   /Library/Frameworks/R.framework/Versions/4.5-x86_64/Resources/lib/libRblas.0.dylib 
## LAPACK: /Library/Frameworks/R.framework/Versions/4.5-x86_64/Resources/lib/libRlapack.dylib;  LAPACK version 3.12.1
## 
## locale:
## [1] C/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
## 
## time zone: America/New_York
## tzcode source: internal
## 
## attached base packages:
## [1] stats4    stats     graphics  grDevices utils     datasets  methods  
## [8] base     
## 
## other attached packages:
##  [1] HDF5Array_1.38.0      h5mread_1.2.0         rhdf5_2.54.0         
##  [4] chihaya_1.10.0        DelayedArray_0.36.0   SparseArray_1.10.0   
##  [7] S4Arrays_1.10.0       abind_1.4-8           IRanges_2.44.0       
## [10] S4Vectors_0.48.0      MatrixGenerics_1.22.0 matrixStats_1.5.0    
## [13] BiocGenerics_0.56.0   generics_0.1.4        Matrix_1.7-4         
## [16] BiocStyle_2.38.0     
## 
## loaded via a namespace (and not attached):
##  [1] cli_3.6.5           knitr_1.50          rlang_1.1.6        
##  [4] xfun_0.53           jsonlite_2.0.0      htmltools_0.5.8.1  
##  [7] sass_0.4.10         rmarkdown_2.30      grid_4.5.1         
## [10] evaluate_1.0.5      jquerylib_0.1.4     fastmap_1.2.0      
## [13] Rhdf5lib_1.32.0     yaml_2.3.10         lifecycle_1.0.4    
## [16] bookdown_0.45       BiocManager_1.30.26 compiler_4.5.1     
## [19] Rcpp_1.1.0          rhdf5filters_1.22.0 XVector_0.50.0     
## [22] lattice_0.22-7      digest_0.6.37       R6_2.6.1           
## [25] bslib_0.9.0         tools_4.5.1         cachem_1.1.0