writeH5AD {zellkonverter} | R Documentation

## Write H5AD

### Description

Write a H5AD file from a SingleCellExperiment object.

### Usage

    writeH5AD(
      sce,
      file,
      X_name = NULL,
      skip_assays = FALSE,
      compression = c("none", "gzip", "lzf")
    )

### Arguments

`sce` | A SingleCellExperiment object.
`file` | String containing a path to write the new `.h5ad` file.
`X_name` | Name of the assay to use as the primary matrix (`X`) of the AnnData object. If `NULL`, the first assay of `sce` will be used by default.
`skip_assays` | Logical scalar indicating whether assay matrices should be ignored when writing to `file`.
`compression` | Type of compression when writing the new `.h5ad` file.

### Details

#### Environment

When first run, this function will instantiate a conda environment containing all of the necessary dependencies. This will not be performed on any subsequent run or if any other zellkonverter function has been run prior to this one.

#### Skipping assays

Setting `skip_assays = TRUE` can occasionally be useful if the matrices in `sce` are stored in a format that is not amenable for efficient conversion to a numpy-compatible format. In such cases, it can be better to create an empty placeholder dataset in `file` and fill it in R afterwards.

#### DelayedArray assays

If `sce` contains any DelayedArray matrices as assays `writeH5AD()` will write them to disk using the rhdf5 package directly rather than via Python to avoid instantiating them in memory. However there is currently an issue which prevents this being done for sparse DelayedArray matrices.

#### Known conversion issues

##### Coercion to factors

The anndata package automatically converts some character vectors to factors when saving `.h5ad` files. This can effect columns of `rowData(sce)` and `colData(sce)` which may change type when the `.h5ad` file is read back into R.

### Value

A `NULL` is invisibly returned.

### Author(s)

Luke Zappia

Aaron Lun

### See Also

`readH5AD()`, to read a SingleCellExperiment file from a H5AD file.

`SCE2AnnData()`, for developers to create an AnnData object from a SingleCellExperiment.

### Examples

    # Using the Zeisel brain dataset
    if (requireNamespace("scRNAseq", quietly = TRUE)) {
        library(scRNAseq)
        sce <- ZeiselBrainData()

        # Writing to a H5AD file
        temp <- tempfile(fileext = ".h5ad")
        writeH5AD(sce, temp)
    }

[Package zellkonverter version 1.2.1 Index]