SessionExprSampleIDs
In some cases when you use a Supplementary File from GEO for RNA-seq data, the sample IDs don't match the GSM IDs in the GEO.samples.csv file. In that case, you can try to run the first function to see if the sample IDs in the expression matrix match any of the sample annotation values in the GEO.samples.csv file. For example, sometimes GEO submitters use a libraryid or title or some other column from that metadata file.
This function is a little fidgety since it requires an exact match of all the annotation values with the expression matrix sample ids. So, you may need to edit the annotations of the samples.csv file in order to force a match.
Like it says, sometimes the expression matrix has very informative sample ids and so you can create a expr.samples.csv file from the sample ids of the expression matrix.