Reading measurement values from a textfile

Vladimir Gajic

Hello@all

I'm quite a C#-beginner. Currently, I'm working on an application for evaluating light measurements. That means, I have to read simple text files containing measurement-data in the following manner:

;MEASUREMENT
;Wave    Value
340    5.48517
341    5.7362
342    6.04807
343    6.31996
344    6.68566
and so on...

My application needs only the Value-component which should be stored into a double array for further calculations. Basically, the whole thing should work something like this (if I'm thinking right)
1. Open a text file using the FileOpen-Dialog
2. Open a Streamreader to read the selected file
3. Ignore anything that is not a number
4. Ignore the Wave-values
5. Store the rest into an string array and convert it to double

I would be grateful for any hints.
Thanks in advance

Vladimir

15 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes13y ago
Accepted answer
Sure, try this variation:

private void button1_Click(object sender, EventArgs e)
{
openFileDialog1.InitialDirectory = "c:\\";
openFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*";
openFileDialog1.FilterIndex = 2;
openFileDialog1.RestoreDirectory = true;

if (openFileDialog1.ShowDialog() == DialogResult.OK)
{
string filePath = openFileDialog1.FileName;
string[] separators = new string[]{" "};
double[] values = File.ReadLines(filePath).Skip(2)
.Select(s => double.Parse(s.Split(separators,StringSplitOptions.RemoveEmptyEntries)[1]
.Replace(':', '.')))
.ToArray();
MessageBox.Show(String.Join("\r\n", values));
}
}
Vladimir Gajic13y ago
again, thanks a lot.
Vladimir Gajic13y ago
Hello again,

one small problem still persists. I used the Linq-Approach posted by Wulpes. It works great as long as my system language setting is set to "en-US". I also managed some globalization so that the application can run on various language-settings. So far so good. Problems occur when my textfile is generated on a system witch uses a decimal colon rather than a decimal point. In that case my calculation is rubbish. Therefore I would like to check the input text file and replace eventual colons by dec. points.

Is there a way to implement this task to your Linq-Code, Wulpes?

Thanks in advance
Vladimir Gajic13y ago
Hello Vulpes,

that worked great. The reason for the exception was the decimal separator witch was a colon instead of decimal point. This could be handled without much problems.

Thanks a lot. From this point I'll explore further but I'm quite shure that questions will arise ;)

Regards
Vladimir
Vulpes13y ago
The most likely reason for the exception is that there are some blank lines in the file or the 'value' field is missing in some of the lines.

You'll then get an 'index out of range' error.

My approach integrated into Iftikar's OpenFileDialog code is as follows:

private void button1_Click(object sender, EventArgs e)
{
openFileDialog1.InitialDirectory = "c:\\";
openFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*";
openFileDialog1.FilterIndex = 2;
openFileDialog1.RestoreDirectory = true;

if (openFileDialog1.ShowDialog() == DialogResult.OK)
{
string filePath = openFileDialog1.FileName;
string[] separators = new string[]{" "};
double[] values = File.ReadLines(filePath).Skip(2)
.Select(s => double.Parse(s.Split(separators, StringSplitOptions.RemoveEmptyEntries)[1]))
.ToArray();
MessageBox.Show(String.Join("\r\n", values));
}
}
Vladimir Gajic13y ago
Hmm. I deleted the code unfortunately. I'll try to restore it and post the exception here. Will take me some time.

Regards
Vladimir
Iftikar Hussain13y ago
what exception you are getting? can you share it?

Regards,
Iftikar
Vladimir Gajic13y ago
Hello Vulpes, trying to figure-out how to quench your code into an openFileDialog and getting a similar exception as in the approach issued by Iftikar. Any ideas? Regards Vladimir
Vladimir Gajic13y ago
So. Just finished the first approach. It issues an exception while adding data to the array.

I'll try the second one, just have to figure-out how to combine with a openFile-dialog.

I'll report.

Regards
Vladimir Gajic13y ago
Guys, you are great. Thanks a lot. I'll try both approaches and will probably have a lot more of questions.

Regards
Vladimr
Vulpes13y ago
Here's an alternative approach which uses LINQ rather than regular expressions.

.NET 4.0 or later required:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

class Program
{
static void Main()
{
string filePath = "measurements.txt";
string[] separators = new string[]{" "};
double[] values = File.ReadLines(filePath).Skip(2)
.Select(s => double.Parse(s.Split(separators, StringSplitOptions.RemoveEmptyEntries)[1]))
.ToArray();

foreach(double value in values) Console.WriteLine(value);
Console.ReadKey();
}
}

The output is:

5.48517
5.7362
6.04807
6.31996
6.68566
Vladimir Gajic13y ago
Thanks a lot!. I try and report.

Regards

Vladimir
Iftikar Hussain13y ago
try like this

private void button1_Click(object sender, EventArgs e)
{
openFileDialog1.InitialDirectory = "c:\\";
openFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*";
openFileDialog1.FilterIndex = 2;
openFileDialog1.RestoreDirectory = true;
ArrayList data = new ArrayList();
if (openFileDialog1.ShowDialog() == DialogResult.OK)
{

string line;
string filename = openFileDialog1.FileName;
using (StreamReader file = new StreamReader(filename))
{
int i = 0;
while ((line = file.ReadLine()) != null)
{
if (i >= 2)
{

RegexOptions options = RegexOptions.None;
Regex regex = new Regex(@"[ ]{2,}", options);

var tempData = regex.Replace(line, @" ");

string[] arrayData = tempData.Split(' ');
data.Add(arrayData[1]);
}
i++;
}
}
}
}

Regards,
Iftikar
Vladimir Gajic13y ago
Hello,

yes, the text file will allways be in that format since it comes from a singular measurement device.

Regards
Vladimir
Iftikar Hussain13y ago
Hi,
Is your textfile will be always content in this format?

Regards,
Iftikar