转录组实战02: 计算非冗余外显子长度之和
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计算非冗余外显子长度
安装gtftools（http://www.genemine.org/gtftools.php）
micromamba activate RNA
micromamba install -c bioconda gtftools
gtftools -l gene_length.txt ~/DataHub/Genomics/GENCODE/release_42/HS.gencode.v42.annotation.gtf可以看到gtftools给出了4种基因长度，也给出了计算的方法，第四种方法也叫非冗余外显子长度，我们接下来使用这个长度计算TPM
Calculate gene lengths. Since a gene may have multiple isoforms, there are multiple ways to calculate gene length based on literature. Three simple ways are considering the mean, median and maximum of the lengths of isoforms as the length of the gene. A fourth way is to calculate the length of merged exons of all isoforms (i.e. non-overlapping exonic length). So, in total, four different types of gene lengths(the mean, median and max of lengths of isoforms of a gene, and the length of merged exons of isoforms of a gene) are provided.
gene mean median longest_isoform merged
ENSG00000287252.3 1546 1323 2751 3266
ENSG00000242268.3 1709 1709 2708 2750
ENSG00000270112.5 1793 1818 4685 10685
ENSG00000280143.1 5326 5326 5326 5326
ENSG00000146083.12 1239 816 4122 5627
ENSG00000158486.15 5952 3404 12567 15023获取基因类型、基因名等信息
gtftools -g gene_info.txt ~/DataHub/Genomics/GENCODE/release_42/HS.gencode.v42.annotation.gtf压缩保存
压缩保存以上两个文件，之后就不用在计算了，以逗号分隔方便之后python读取。
import pandas as pd
g1 = pd.read_csv("gene_info.txt",sep='\t',index_col=4,header=None)
g1.columns = ["Chr","Start","Stop","Strand","Symbol","GeneType"]
g2 = pd.read_csv("gene_length.txt",sep='\t',index_col=0,usecols=["gene","merged"])
g = pd.merge(g1,g2,left_index=True,right_index=True)
g.insert(0,column="Ensembl",value=g.index)
g.rename(columns={"merged":"Length"},inplace=True)
g.sort_values("Chr",inplace=True)
g.to_csv("hg38_gene_info_v42.csv.gz",index=False)给count添加基因信息
修改下“转录组实战01: 从数据下载到定量fastp+STAR“中的代码，合并count数据饿时候给gene添加信息，这样比较像测序公司给的表达量数据。
# 现在的目录是~/Project/Human_16_Asthma_Bulk
from pathlib import Path
import pandas as pd
import datatable as dt
dir="alignment/STAR"
count_list = []
tpm_list = []
paths = Path(dir).glob("*ReadsPerGene.out.tab")
for x,y in enumerate(list(paths)):
if x < 1:
Ensembl = pd.read_csv(y,usecols=[0],sep='\t',skiprows=4,header=None)
Ensembl.rename(columns={0:'Ensembl'},inplace=True)
_count_df = pd.read_csv(y,usecols=[1],sep='\t',skiprows=4,header=None)
count_list.append(_count_df.rename(columns={1:y.name.split('Reads')[0]}))
count_df = pd.concat(count_list,axis=1)
count_df.insert(0,column='Ensembl',value=Ensembl)
count = pd.merge(gene_info,count_df,on="Ensembl")
dt.Frame(count).to_csv('star_count.csv.gz')新的表达矩阵如下所示
Ensembl Chr Start Stop Strand Symbol GeneType Length SRR1039516 SRR1039522 SRR1039508 SRR1039523 SRR1039511 SRR1039510 SRR1039514 SRR1039521 SRR1039512 SRR1039513 SRR1039519 SRR1039515 SRR1039520 SRR1039509 SRR1039518 SRR1039>
ENSG00000130762.15 1 3454664 3481113 + ARHGEF16 protein_coding 5324 2 0 1 0 1 1 1 0 2 0 0 0 1 0 1 1
ENSG00000117472.10 1 46175072 46185962 + TSPAN1 protein_coding 2370 16 2 1 2 2 4 11 1 11 1 17 11 1 0 8 9
ENSG00000227857.2 1 46134530 46139081 + ENSG00000227857 lncRNA 339 0 1 2 0 0 2 0 0 2 0 0 1 1 0 0 0
ENSG00000233114.2 1 46104949 46105175 + ENSG00000233114 processed_pseudogene 226 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。
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原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。
如有侵权，请联系 cloudcommunity@tencent.com 删除。
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