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Filtering genes gives incorrect number of genes in filtered list

Hi,

I have a list of genes (long_list) from which I want to filter a list with genes of interest (goi) to retrieve a filtered list of genes (genes_filtered). The gois are all expected to be contained in the long_list.

However, when I filter for the gois, I always retrieve four extra genes.

genes_filtered <- long_list[long_list$ensembl %in% goi$ensembl,]

Dimensions of the lists:

dim(long_list)[1]
> 15251
dim(goi)[1]
> 11221
dim(genes_filtered)[1]
> 11225 #Should be 11221 (same as goi)

I have tried the following to get to the bottom if this.

Checking duplicates in genes_filtered, long_list, and goi:

dim(genes_filtered[duplicated(genes_filtered$ensembl),])[1]
> [1] 0
dim(long_list[duplicated(long_list$ensembl),])[1]
> [1] 0
dim(goi[duplicated(goi$ensembl),])[1]
> NULL

Checking missing values:

sum(is.na(genes_filtered))
> [1] 0
sum(is.na(long_list))
> [1] 0
sum(is.na(goi))
> [1] 0

Checking values contained in genes_filtered but not in goi:

# 1: Using lists
genes_filtered[!(genes_filtered$ensembl %in% goi$ensembl)]
data frame with 0 columns and 11125 rows

# 2: Extracting columns first from lists
f <- genes_filtered$ensembl
g <- goi$ensembl

g[!(g %in% f)]
[1] "ENSG00000283208" "ENSG00000284292" "ENSG00000262633" ...

Method 2 retrieves a list of in total 96 genes, which is not expected.

Can anyone explain why the filtering method at the top of the post does not work and possibly suggest a correct way?

filtering genes r
• 3,368 views • link
written by bioneer • bioneer

Very strange, what version of R are you using? Can you posts the two lists for others to compare?

• 0 views • link
written by Mark Mark

I'm using R 4.1.2

R version 4.1.2 (2021-11-01)

About posting the lists: They are both quite long, what is the best way to post them?

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written by bioneer • bioneer

Sorry, I cannot open that page.

• 0 views • link
written by bioneer • bioneer

try github then

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written by Mark Mark

According to what you provide, I have on my console :

dim(genes_filtered)[1]
[1] 11125

I can't see any problem, are you sure you did not make a copy-paste error ?

• 0 views • link
written by Basti • Basti

Based on the data provided dim(long_list)[1] retuns 15202 which is not what mentioned in the post. To figure out the issue it is really important to work on the exact same datasets.

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written by Hamid Ghaedi Hamid Ghaedi

1 answer

I can't believe you and I missed this. It took me a while to workout what the issue was:

length(ll) # 15202
length(goi) # 11221
sum(ll %in% goi) # 11125

In case you missed it:

11221
11125

The difference? 96. You said:

Method 2 retrieves a list of in total 96 genes, which is not expected.

Not sure why we discounted this, but method 2 is correct. There's a difference of 96 genes between goi and long_list. Here's another method that shows this:

library(dplyr)
goi_df = data.frame(id = goi,
                    goi_id = 1:length(goi))
ll_df = data.frame(id = ll,
                    ll_id = 1:length(ll))
combine = left_join(ll_df, goi_df, by = "id")

sum(is.na(combine$goi_id)) # 4077

15202 - 4077 # 11125

So which genes of interest are missing?

setdiff(goi, combined_subset$id)

[1] "ENSG00000283208" "ENSG00000284292" "ENSG00000262633" "ENSG00000258472" "ENSG00000276017" "ENSG00000283809" "ENSG00000277971" "ENSG00000277639" [9] "ENSG00000269755" "ENSG00000268400" "ENSG00000258311" "ENSG00000261341" "ENSG00000268750" "ENSG00000279765" "ENSG00000226690" "ENSG00000284526" [17] "ENSG00000267740" "ENSG00000261884" "ENSG00000267426" "ENSG00000170846" "ENSG00000283580" "ENSG00000267314" "ENSG00000283782" "ENSG00000283761" [25] "ENSG00000214265" "ENSG00000183889" "ENSG00000262165" "ENSG00000275063" "ENSG00000277856" "ENSG00000182584" "ENSG00000267120" "ENSG00000259529" [33] "ENSG00000258465" "ENSG00000203546" "ENSG00000282246" "ENSG00000187186" "ENSG00000278384" "ENSG00000124593" "ENSG00000273748" "ENSG00000277263" [41] "ENSG00000285085" "ENSG00000256591" "ENSG00000173915" "ENSG00000156411" "ENSG00000214654" "ENSG00000284976" "ENSG00000151131" "ENSG00000130921" [49] "ENSG00000174206" "ENSG00000125149" "ENSG00000088854" "ENSG00000285217" "ENSG00000171159" "ENSG00000104957" "ENSG00000198003" "ENSG00000160124" [57] "ENSG00000018610" "ENSG00000187866" "ENSG00000156504" "ENSG00000156500" "ENSG00000051009" "ENSG00000151553" "ENSG00000158863" "ENSG00000285382" [65] "ENSG00000275464" "ENSG00000287542" "ENSG00000232593" "ENSG00000162929" "ENSG00000276033" "ENSG00000274847" "ENSG00000072415" "ENSG00000105926" [73] "ENSG00000198899" "ENSG00000228253" "ENSG00000198804" "ENSG00000198712" "ENSG00000198938" "ENSG00000198727" "ENSG00000198888" "ENSG00000198763" [81] "ENSG00000198840" "ENSG00000198886" "ENSG00000212907" "ENSG00000198786" "ENSG00000198695" "ENSG00000258724" "ENSG00000228049" "ENSG00000285437" [89] "ENSG00000143303" "ENSG00000205045" "ENSG00000102125" "ENSG00000285053" "ENSG00000283268" "ENSG00000011638" "ENSG00000243667" "ENSG00000225528"

Tricky tricky. Hope this helps.

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written by Mark Mark

Hi Mark, Thank you so much for digging into the issue and for finding what I missed! The assumption that all genes of interest would be contained in the long list was apparently wrong.

Again, thank you!

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written by bioneer • bioneer

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