norm_data {spatialHeatmap} | R Documentation

## Normalize Sequencing Count Matrix

### Description

This function normalizes sequencing count data. It accepts the count matrix and sample metadata (optional) in form of `SummarizedExperiment` or `data.frame`. In either class, the columns and rows of the count matix should be sample/conditions and genes respectively.

### Usage

    norm_data(data, norm.fun = "CNF", parameter.list = NULL, data.trans = "none")

### Arguments

`data` | An object of `data.frame` or `SummarizedExperiment`. In either case, the columns and rows should be sample/conditions and assayed items (e.g. genes, proteins, metabolites) respectively. If `data.frame`, the column names should follow the naming scheme "sample__condition". The "sample" is a general term and stands for cells, tissues, organs, etc., where the values are measured. The "condition" is also a general term and refers to experiment treatments applied to "sample" such as drug dosage, temperature, time points, etc. If certain samples are not expected to be colored in "spatial heatmaps" (see `spatial_hm`), they are not required to follow this naming scheme. In the downstream interactive network (see `network`), if users want to see node annotation by mousing over a node, a column of row item annotation could be optionally appended to the last column. In the case of `SummarizedExperiment`, the `assays` slot stores the data matrix. Similarly, the `rowData` slot could optionally store a data frame of row item anntation, which is only relevant to the interactive network. The `colData` slot usually contains a data frame with one column of sample replicates and one column of condition replicates. It is crucial that replicate names of the same sample or condition must be identical. E.g. If sampleA has 3 replicates, "sampleA", "sampleA", "sampleA" is expected while "sampleA1", "sampleA2", "sampleA3" is regarded as 3 different samples. If original column names in the `assay` slot already follow the "sample__condition" scheme, then the `colData` slot is not required at all. In the function `spatial_hm`, this argument can also be a numeric vector. In this vector, every value should be named, and values expected to color the "spatial heatmaps" should follow the naming scheme "sample__condition". In certain cases, there is no condition associated with data. Then in the naming scheme of `data frame` or `vector`, the "__condition" part could be discarded. In `SummarizedExperiment`, the "condition" column could be discarded in `colData` slot. Note, regardless of data class the double underscore is a special string that is reserved for specific purposes in "spatialHeatmap", and thus should be avoided for naming feature/samples and conditions.
`norm.fun` | One of the normalizing functions: "CNF", "ESF", "VST", "rlog". Specifically, "CNF" stands for `calcNormFactors` from edgeR (McCarthy et al. 2012), and "EST", "VST", and "rlog" is equivalent to `estimateSizeFactors`, `varianceStabilizingTransformation`, and `rlog` from DESeq2 respectively (Love, Huber, and Anders 2014). If "none", no normalization is applied. The default is "CNF". The parameters of each normalization function are provided through `parameter.list`.
`parameter.list` | A list of parameters for each normalizing function assigned in `norm.fun`. The default is NULL and `list(method='TMM')`, `list(type='ratio')`, `list(fitType='parametric', blind=TRUE)`, `list(fitType='parametric', blind=TRUE)` is internally set for "CNF", "ESF", "VST", "rlog" respectively. Note the slot name of each element in the list is required. E.g. `list(method='TMM')` is expected while `list('TMM')` would cause errors. Complete parameters of "CNF": https://www.rdocumentation.org/packages/edgeR/ versions/3.14.0/topics/calcNormFactors Complete parameters of "ESF": https://www.rdocumentation.org/packages/ DESeq2/versions/1.12.3/topics/estimateSizeFactors Complete parameters of "VST": https://www.rdocumentation.org/packages/ DESeq2/versions/1.12.3/topics/varianceStabilizingTransformation Complete parameters of "rlog": https://www.rdocumentation.org/packages/ DESeq2/versions/1.12.3/topics/rlog
`data.trans` | One of "log2", "exp2", and "none", corresponding to transform the count matrix by "log2", "2-based exponent", and "no transformation" respecitvely. The default is "none".

### Value

If the input data is `SummarizedExperiment`, the retured value is also a `SummarizedExperiment` containing normalized data matrix and metadata (optional). If the input data is a `data.frame`, the returned value is a `data.frame` of normalized data and metadata (optional).

### Author(s)

Jianhai Zhang jzhan067@ucr.edu; zhang.jianhai@hotmail.com
Dr. Thomas Girke thomas.girke@ucr.edu

### References

SummarizedExperiment: SummarizedExperiment container. R package version 1.10.1
R Core Team (2018). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL https://www.R-project.org/
McCarthy, Davis J., Chen, Yunshun, Smyth, and Gordon K. 2012. "Differential Expression Analysis of Multifactor RNA-Seq Experiments with Respect to Biological Variation." Nucleic Acids Research 40 (10): 4288–97
Keays, Maria. 2019. ExpressionAtlas: Download Datasets from EMBL-EBI Expression Atlas
Love, Michael I., Wolfgang Huber, and Simon Anders. 2014. "Moderated Estimation of Fold Change and Dispersion for RNA-Seq Data with DESeq2." Genome Biology 15 (12): 550. doi:10.1186/s13059-014-0550-8
McCarthy, Davis J., Chen, Yunshun, Smyth, and Gordon K. 2012. "Differential Expression Analysis of Multifactor RNA-Seq Experiments with Respect to Biological Variation." Nucleic Acids Research 40 (10): 4288–97
Cardoso-Moreira, Margarida, Jean Halbert, Delphine Valloton, Britta Velten, Chunyan Chen, Yi Shao, Angélica Liechti, et al. 2019. “Gene Expression Across Mammalian Organ Development.” Nature 571 (7766): 505–9

### See Also

`calcNormFactors` in edgeR, and `estimateSizeFactors`, `varianceStabilizingTransformation`, `rlog` in DESeq2.

### Examples

    ## In the following examples, the 2 toy data come from an RNA-seq analysis on development of 7
    ## chicken organs under 9 time points (Cardoso-Moreira et al. 2019). For conveninece, they are
    ## included in this package. The complete raw count data are downloaded using the R package
    ## ExpressionAtlas (Keays 2019) with the accession number "E-MTAB-6769". Toy data1 is used as
    ## a "data frame" input to exemplify data of simple samples/conditions, while toy data2 as
    ## "SummarizedExperiment" to illustrate data involving complex samples/conditions.

    ## Set up toy data.

    # Access toy data1.
    cnt.chk.simple <- system.file('extdata/shinyApp/example/count_chicken_simple.txt',
    package='spatialHeatmap')
    df.chk <- read.table(cnt.chk.simple, header=TRUE, row.names=1, sep='\t', check.names=FALSE)
    # Columns follow the namig scheme "sample__condition", where "sample" and "condition" stands
    # for organs and time points respectively.
    df.chk[1:3, ]

    # A column of gene annotation can be appended to the data frame, but is not required.
    ann <- paste0('ann', seq_len(nrow(df.chk))); ann[1:3]
    df.chk <- cbind(df.chk, ann=ann)
    df.chk[1:3, ]

    # Access toy data2.
    cnt.chk <- system.file('extdata/shinyApp/example/count_chicken.txt', package='spatialHeatmap')
    count.chk <- read.table(cnt.chk, header=TRUE, row.names=1, sep='\t')
    count.chk[1:3, 1:5]

    # Store toy data2 in "SummarizedExperiment".
    library(SummarizedExperiment)
    se.chk <- SummarizedExperiment(assay=count.chk)

    # Normalize raw count data. The normalizing function "calcNormFactors" (McCarthy et al. 2012)
    # with default settings is used.
    df.nor.chk <- norm_data(data=df.chk, norm.fun='CNF', data.trans='log2')
    se.nor.chk <- norm_data(data=se.chk, norm.fun='CNF', data.trans='log2')

[Package spatialHeatmap version 1.0.0 Index]