Reading from .csv-file into double-array

Question

I have a question concerning LINQ queries and return types. I just want to read values from a .csv file, where there are double values separated by semicolon like this:

0,016;0,010;-0,020;-0,014;0,020;0,016;-0,019;-0,014;0,023;

The reading from the file works fine with the following statement:

        double pdValue;
        double[] pdValues;

        var values = File.ReadAllLines(path)
            .Select(a => a.Split(';')
            .Select(str => double.TryParse(str, out pdValue) ? pdValue : 0));

        pdValues = values.ToArray();

But the last line returns the 'Cannot implicitly convert System.Collections.Generic.IENumerable< double> to double[]' error. Trying to get it to work with array changes the error to 'Cannot implicitly convert System.Collections.Generic.IENumerable< double>[] to double[]'.

When debugging, I can already see that the values variable holds all values from the file (somehow) as array...

I could not find anything yet, what could give me a hint on what exactly I am doing wrong here. Can anybody help me?

Thanks in advance!

Ok you said the values variable holds all values from the file (somehow) as array.. err cos you said a.Split(';') .. so now its an array of strings... — BugFinder
– BugFinder, Commented Apr 4, 2017 at 9:02
It's more usefull to use the File.ReadLines instead of the File.ReadAllLines, because the File.ReadLines streams the data instead of loading it full into the memory. — Jeroen van Langen
– Jeroen van Langen, Commented Apr 4, 2017 at 9:05
The file contains more than one line? So It would be a double[][] What do you need as result? double[][] or double[] (all lines merged) — Jeroen van Langen
– Jeroen van Langen, Commented Apr 4, 2017 at 9:07

Omar Muscatello · Accepted Answer · 2017-04-04 09:09:54Z

3

Look at the values variable type which is IEnumerable<IEnumerable<double>>. You should use this code:

 var values = File.ReadAllLines(path)
            .SelectMany(a => a.Split(';')
            .Select(str => double.TryParse(str, out pdValue) ? pdValue : 0));

pdValues = values.ToArray();

answered Apr 4, 2017 at 9:09

Omar Muscatello

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1 Comment

mrpip Over a year ago

Thanks so much, the .SelectMany statement fixed it!

Ranjith V · Accepted Answer · 2017-04-04 09:14:36Z

1

The ReadAllLine method will return an array of strings ( Lets say Array A). The Split method that you have used is going to give you a string array split by ";" for every item of Array A. So the end result would be an array of array. That is the reason for the error.

You can try :

var values = File.ReadAllLines(path).ToString()
            .Split(';').Select(str => double.TryParse(str, out pdValue) ? pdValue : 0);

answered Apr 4, 2017 at 9:14

Ranjith V

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