You need to be careful of precedence. Compare

Thank you for pointing this out. Yes, it does the trick:

In[282]:= (Select[stringLines, Not@*StringStartsQ["#"]]//DeleteCases[#, ""]&)===(Select[stringLines, Not@*StringStartsQ["#"]]/. "" -> Nothing)

Out[282]= True

The following method will leave an empty item in the result:

Select[stringLines, Not@*StringStartsQ["#"]]

As shown below:

In[112]:= (*If you actually want the individual lines,*)

stringLines = Import[file, {"Text", "Lines"}];

(*You could use Select:
*)

Select[stringLines, Not@*StringStartsQ["#"]][[1;;5]]

Out[113]= {"", "x,y,z", "x,y+1/8,z+7/8", "x,y+1/4,z+3/4", \
"x,y+3/8,z+5/8"}

I tried the following method, but it could not achieve the purpose of removing the above empty item:

Select[stringLines, Not@*StringStartsQ["#"]&& #=!=""&]

In fact, the above code will give you the following strange result:

{}

What's even stranger is that I tried the different methods below, and their results were different:

In[249]:= Select[stringLines, Not@*StringStartsQ["#"]]//DeleteCases[#, ""]&;
%===Select[stringLines, Not@*StringStartsQ["#"]]/. "" -> Nothing

Out[250]= False

But the check below confirms that they are exactly the same:

In[278]:= listA=Select[stringLines, Not@*StringStartsQ["#"]]//DeleteCases[#, ""]&; 
listB=Select[stringLines, Not@*StringStartsQ["#"]]/. "" -> Nothing;
ForAll[MapThread[SameQ, {listA, listB}],True]

Out[280]= True

I've attached the testing file here for your information.

Regards, Zhao

Attachments:

SG229me3.txt