1、直接測試

dir()     ## 列出當前目錄中所有檔案
myfile <- list.files()   ## 將當前目錄中的所有檔案都儲存為字元
myfile
gzfile <- myfile[grep(myfile, pattern =".gz$")]   ## 提取當前目錄中以.gz結尾的檔案
gzfile
txtfile <- myfile[grep(myfile, pattern = ".txt$")]   ## 提取當前目錄中以.txt結尾的檔案
txtfile

> dir()   ## 列出所有檔案
[1] "GSE148812_family.soft
 
"                   
[2] "GSE148812_family.soft.gz"                
[3] "GSE148812_genotyping_results.txt"        
[4] "GSE148812_genotyping_results.txt.gz"     
[5] "GSE148812_RAW.tar"                       
[6] "GSM4481589_8378315049_R05C01_Grn.idat"   
[7] "GSM4481589_8378315049_R05C01_Grn.idat.gz"
[8] "
 
GSM4481589_8378315049_R05C01_Red.idat"   
[9] "GSM4481589_8378315049_R05C01_Red.idat.gz"
> myfile <- list.files()   ## 所有檔案賦值給一個變數
> myfile
[1] "GSE148812_family.soft"                   
[2] "GSE148812_family.soft.gz"                
[3] "GSE148812_genotyping_results.txt"        
[4] "GSE148812_genotyping_results.txt.gz
 
"     
[5] "GSE148812_RAW.tar"                       
[6] "GSM4481589_8378315049_R05C01_Grn.idat"   
[7] "GSM4481589_8378315049_R05C01_Grn.idat.gz"
[8] "GSM4481589_8378315049_R05C01_Red.idat"   
[9] "GSM4481589_8378315049_R05C01_Red.idat.gz"
> gzfile <- myfile[grep(myfile, pattern =".gz$")]   ## 提取以.gz結尾的檔案
> gzfile
[1] "GSE148812_family.soft.gz"                
[2] "GSE148812_genotyping_results.txt.gz"     
[3] "GSM4481589_8378315049_R05C01_Grn.idat.gz"
[4] "GSM4481589_8378315049_R05C01_Red.idat.gz"
> txtfile <- myfile[grep(myfile, pattern = ".txt$")]   ##提取以.txt結尾的檔案
> txtfile
[1] "GSE148812_genotyping_results.txt"

> gsefile <- myfile[grep(myfile, pattern = "^GSE")]   ## 提取以GSE開頭的檔案
> gsefile
[1] "GSE148812_family.soft"              
[2] "GSE148812_family.soft.gz"           
[3] "GSE148812_genotyping_results.txt"   
[4] "GSE148812_genotyping_results.txt.gz"
[5] "GSE148812_RAW.tar"    

參考：https://zhuanlan.zhihu.com/p/378404523