Question: How to group gene dataset and run t.test for each row for every gene in R?
0
gravatar for ishackm
27 days ago by
ishackm60
ishackm60 wrote:

Hi all,

I have the following gene dataset:

enter image description here

I would like to group the samples into the following please:

Malignant cell samples are: AOCS1, G33, G164

Fibroblasts are: G342, G351, G369

After I grouped them into the two sample categories, Malignant and Fibroblast, I would like to do the test test for each row of the genes,

For example,

enter image description here

I am using R studio

I am new to this kind of analysis so any help will be greatly appreciated.

Many Thanks,

Ishack

rna-seq R • 115 views
ADD COMMENTlink modified 27 days ago by shawn.w.foley720 • written 27 days ago by ishackm60

If you are getting this data from raw RNA-Seq data your best bet is to use a well established method like DESeq2 or edgeR or limma.

ADD REPLYlink written 27 days ago by benformatics870

Even if you do not have the raw data it is a much better solution to use limma via its trend functionality! Those values you post are mostly likely not normal distributed so you should NOT use a t-test!

ADD REPLYlink written 21 days ago by kristoffer.vittingseerup1.8k
1
gravatar for shawn.w.foley
27 days ago by
shawn.w.foley720
USA
shawn.w.foley720 wrote:

For a problem like this you want to look into the apply function in R. This function will let you perform a function row-wise or column-wise on a dataframe or matrix.

From the help menu: apply(X, MARGIN, FUN, ...) where X is your dataframe/matrix, MARGIN is either 1 for row-wise or 2 for column-wise, and FUN is the function that you want to perform. Depending on what you want to do, you can have a base FUN such as median or sum, or you can define your own function(x), where x is each row (or column) in your dataframe.

So for the example of dataframe df where columns 2-4 are Malignant and 5-7 are fibroblast you can run:

pValues <- apply(df, 1, function(x) t.test(x[2:4],x[5:7])$p.value)

This will take df and for each row (indicated by the 1, as opposed to each column) it will perform function(x), whereby a t-test is performed on the elements 2-4 compared to 5-7, and the p-value is reported (hence the $p.value). This will perform that function for each row, and store the p-values in the vector pValues.

ADD COMMENTlink written 27 days ago by shawn.w.foley720
1

Thanks very much for your help Shawn, very much appreciated for the clear explanation

ADD REPLYlink written 27 days ago by ishackm60
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