Question

Using vcfR to group variants per annotations

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13 months ago

Begonia_pavonina ▴ 150

I am using the vcfR package for R in order to group the SNPs variants of a VCF file per annotations. With vcfR,I have built a chrom object with a VCF file, a FASTA reference file, and a GFF annotation file describing the exons/introns in my sequence.

I have been following the documentation related to the package presenting the chrom objects to understand how to manipulate them. https://knausb.github.io/vcfR_documentation/chromR_object.html

But the documentation just explain how to make a plot and explore the object, not how to group information.

I know that the following code can give genotypes:

extract.gt(chrom)

And that this one can access to the annotations:

chrom@ann

But I have not found a way to relate them and export the information in a dataframe. Has anyone worked on this? Is there a tutorial you would recommand for this kind of data manipulation?

vcf vcfR R • 932 views

ADD COMMENT • link updated 13 months ago by dthorbur ★ 1.9k • written 13 months ago by Begonia_pavonina ▴ 150

score 2 · Accepted Answer · 2023-03-03

Hey, here is how I have done it in the past:

library(data.table) 
library(dplyr)

temp_chrom <- vcfR::read.vcfR(vcf_path)
temp_gt <- temp_chrom@gt[,] %>% as.data.table
temp_out <- data.table(CHR = temp_chrom@fix[,"CHROM"], POS = temp_chrom@fix[,"POS"] %>% as.integer(), 
        REF = temp_chrom@fix[,"REF"], 
        ALT = temp_chrom@fix[,"ALT"])

Simplified_VCF <- cbind(temp_out, temp_gt)

Here is a snippet of the output:

> Simplified_VCF
               CHR      POS REF ALT                    FORMAT                                    Collarless_A_val                                    Collarless_B_val                                    Collarless_C_val
     1: CM029350.1      100   T   A GT:AD:DP:GQ:PGT:PID:PL:PS                        0/0:34,0:34:93:.:.:0,93,1395                       0/0:40,0:40:99:.:.:0,114,1710                        0/0:39,0:39:58:.:.:0,58,1368
     2: CM029350.1      106   A   G GT:AD:DP:GQ:PGT:PID:PL:PS                        0/0:34,0:34:90:.:.:0,90,1350                       0/0:44,0:44:99:.:.:0,120,1800                        0/0:43,0:43:48:.:.:0,48,1424
     3: CM029350.1      242   A   C            GT:AD:DP:GQ:PL                           0/0:37,0:37:99:0,102,1530                           0/0:47,0:47:99:0,101,1709                           0/0:49,0:49:99:0,112,1800
     4: CM029350.1     1509   G   A            GT:AD:DP:GQ:PL                           1/1:0,57:57:99:2109,170,0                           1/1:0,83:83:99:3042,247,0                           1/1:0,70:70:99:2452,209,0
     5: CM029350.1     1763   G   A            GT:AD:DP:GQ:PL                           0/0:43,0:43:99:0,106,1422                           0/0:54,0:54:99:0,106,1516                           0/0:62,0:62:99:0,118,1800
    ---                                                                                                                                                                                                                  
248278: CM029350.1 27080198   G   C            GT:AD:DP:GQ:PL                           1/1:0,47:47:99:1768,141,0                           1/1:0,66:66:99:2439,198,0                           1/1:0,64:64:99:2307,191,0
248279: CM029350.1 27080215   A   T            GT:AD:DP:GQ:PL                           1/1:0,49:49:99:1816,146,0                           1/1:0,59:59:99:2152,176,0                           1/1:0,66:66:99:2498,198,0
248280: CM029350.1 27080272   A   G GT:AD:DP:GQ:PGT:PID:PL:PS 1|1:0,44:44:99:1|1:27080272_A_G:1968,132,0:27080272 1|1:0,48:48:99:1|1:27080272_A_G:2141,144,0:27080272 1|1:0,40:40:99:1|1:27080272_A_G:1796,120,0:27080272
248281: CM029350.1 27080280   T   C GT:AD:DP:GQ:PGT:PID:PL:PS 1|1:0,42:42:99:1|1:27080272_A_G:1890,126,0:27080272 1|1:0,45:45:99:1|1:27080272_A_G:2025,135,0:27080272 1|1:0,40:40:99:1|1:27080272_A_G:1796,120,0:27080272
248282: CM029350.1 27080293   G   A GT:AD:DP:GQ:PGT:PID:PL:PS 1|1:0,34:34:99:1|1:27080272_A_G:1530,102,0:27080272 1|1:0,44:44:99:1|1:27080272_A_G:1980,132,0:27080272 1|1:0,36:36:99:1|1:27080272_A_G:1620,108,0:27080272

The order of rows accessed by @[fix|gt|ann] are preserved, so you can use cbind to bind dataframes. If you do not want to use data.table then replace as.data.table with as.data.frame.