plot_molecules {lipidr} | R Documentation

## Informative plots to investigate individual lipid molecules

### Description

`lipidr` supports three types of plots for to visualize at lipid molecules.
`cv` plots a bar chart for coefficient of variation of lipid molecules. This plot type is usually used to investigate the CV in lipid intensity or retention time, in QC samples.
`sd` plots a bar chart for standard deviations of a certain measure in each lipid. This plot type is usually used to look at standard deviation of intensity for each lipid, but can also be used to look at different measures such as `Retention Time`, to ensure all lipids elute within expected range.
`boxplot` plots a boxplot chart to examine the distribution of values per lipid. This plot type is usually used to look at intensity distribution for each lipid, but can also be used to look at different measures, such as `Retention Time` or `Background`.

### Usage

    plot_molecules(
      data,
      type = c("cv", "sd", "boxplot"),
      measure = "Area",
      log = TRUE,
      color = "Class"
    )

### Arguments

`data` | LipidomicsExperiment object.
`type` | plot type, either `cv`, `sd` or `boxplot`. Default is `cv`.
`measure` | Which measure to plot the distribution of: usually Area, Area Normalized or Height. Default is `Area`
`log` | Whether values should be log2 transformed (Set FALSE for retention time). Default is `TRUE`
`color` | The column name of a row annotation to be used as color

### Value

A ggplot object.

### Examples

    data(data_normalized)
    d_qc <- data_normalized[, data_normalized$group == "QC"]

    # plot the variation in intensity and retention time of all measured
    #   lipids in QC samples
    plot_molecules(d_qc, "cv", "Area")
    plot_molecules(d_qc, "cv", "Retention Time", log = FALSE)

    # plot the variation in intensity, RT of ISTD (internal standards)
    #   in QC samples
    d_istd_qc <- data_normalized[
      rowData(data_normalized)$istd,
      data_normalized$group == "QC"
    ]
    plot_molecules(d_istd_qc, "sd", "Area")
    plot_molecules(d_istd_qc, "sd", "Retention Time", log = FALSE)

    plot_molecules(d_istd_qc, "boxplot")
    plot_molecules(d_istd_qc, "boxplot", "Retention Time", log = FALSE)

[Package lipidr version 2.4.0 Index]