Existence of a column in a table in an if loop

• To: mathgroup at smc.vnet.net
• Subject: [mg125339] Existence of a column in a table in an if loop
• From: maria giovanna dainotti <mariagiovannadainotti at yahoo.it>
• Date: Thu, 8 Mar 2012 04:36:10 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

```Dear Mathgroup,
I have the following problem:
when I do mean = Mean[Table[s5[[i, 5]] for some data the last column doen't exists, how can i ask the program to compute the mean only if the column exists.
Thanks,
Best regards,
Maria

data5 = {{50315, "111063"}}

Do[
ID = data5[[i, 2]];
s = Import[
"http://www.swift.ac.uk/xrt_curves/00"; <> ID <> "/curve2.qdp",
"Text"];
background = StringPosition[s, "! PC background data"][[1, 1]];
s1 = StringDrop[s, background];
s2 = StringPosition[s1, "NO NO NO NO NO NO"][[1,=0A 1]];
s3 = StringDrop[s1, -s2];
s4 = Export["s3.txt", s3, "Table"];
s5 = Import["s3.txt", "Table"];
mean = Mean[Table[s5[[i, 5]], {i, 3, Length[s5]}]],
{i, 1, Length[data5]}]

```

• Prev by Date: OpenCL OpenCLFractalRender3D invalid binary error
• Next by Date: Re: new functional operator
• Previous by thread: Re: OpenCL OpenCLFractalRender3D invalid binary error
• Next by thread: Using Mathematica to typeset books