Hello I have a set of daily meteo data, using the expression :

f <- list.files(getwd(), include.dirs=TRUE, recursive=TRUE, pattern= "PREC") 

I select only the files of Precipitation

I wonder how to select only files for example of January, the one for example named 20170103 (yyyymmdd) , so the one named yyyy01dd....

the files are named in this way: "PREC_20010120.grd".

CodePudding user response：

Try pattern='PREC_\\d{4}01\\d[2].*'.

• PREC_ literally
• \\d{4} four digits
• 01 '"01" literally
• \\d{2} two digits
• .* any character repeatedly

CodePudding user response：

Thank you , but I retrieved only 35 items instead of 31 days * 10 years what's wrong ?

[1] "20100102/PREC_20100102.tif" "20100112/PREC_20100112.tif"
[3] "20100122/PREC_20100122.tif" "20110102/PREC_20110102.tif"
[5] "20110112/PREC_20110112.tif" "20110122/PREC_20110122.tif"
[7] "20120102/PREC_20120102.tif" "20120112/PREC_20120112.tif"
[9] "20120122/PREC_20120122.tif" "20130102/PREC_20130102.tif"
[11] "20130112/PREC_20130112.tif" "20130122/PREC_20130122.tif"
[13] "20140102/PREC_20140102.tif" "20140112/PREC_20140112.tif"
[15] "20140122/PREC_20140122.tif" "20150102/PREC_20150102.tif"
[17] "20150112/PREC_20150112.tif" "20150122/PREC_20150122.tif"
[19] "20160102/PREC_20160102.tif" "20160112/PREC_20160112.tif"
[21] "20160122/PREC_20160122.tif" "20170102/PREC_20170102.tif"
[23] "20170112/PREC_20170112.tif" "20170122/PREC_20170122.tif"
[25] "20180102/PREC_20180102.tif" "20180112/PREC_20180112.tif"
[27] "20180122/PREC_20180122.tif" "20190102/PREC_20190102.tif"
[29] "20190112/PREC_20190112.tif" "20190122/PREC_20190122.tif"
[31] "20200102/PREC_20200102.tif" "20200112/PREC_20200112.tif"
[33] "20200122/PREC_20200122.tif" "20210102/PREC_20210102.tif"
[35] "20210112/PREC_20210112.tif" "20210122/PREC_20210122.tif"