Extracting rows on basis of specific column values in R

Question

[sidrah.maryam]

I have a dataframe that contains various fields. An instance being:

Protein Code Sequence CODON XYZ L AATTGCTA MET ABC K ATTGCTA MET-2 JKL B GCTTATA LYS-2

I want to extract information of all the elements in which the column CODON ends with "-2".

Like in this case i get : ABC K ATTGCTA MET-2 JKL B GCTTATA LYS-2

Please suggest the answer.

I used :

od_lig <- filter(odor_lig, CODON== "$-2")

But I got blank data.

[rezaeir75]

Because you are using a regular expression and filter doesn't understand regex directly. Wrap your regex in grepl and also give it the target column and wrap that in your filter function.

[Ido Tamir]

please work through any of the many online R tutorials. You could also look up "how to ask questions" and unfortunately it looks like a correct tagging of posts tutorial is also necessary. Maybe you think the $ would signify a regex end matching? try endsWith

[rpolicastro]

What does a value in the CODON column actually look like?

Answer 1

[Shalu Jhanwar]

Suppose the entire protein Code Sequence is read in one column (codon) of the data frame. You can use the below code in R script to extract rows ends with "-2":

grepl("-2$",df$codon)

[sidrah.maryam]

Thank you so much for your help

[Ram]

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