I want to remove a column with a specific value. The code below is what I used to remove a row. Can I reverse this to remove a column?
int row = comboBox1.SelectedIndex;
string verw = Convert.ToString(txtChange.Text);
List<string> lines = new List<string>();
using (StreamReader reader = new StreamReader(System.IO.File.OpenRead(filepath)))
{
string line;
while ((line = reader.ReadLine()) != null)
{
if (line.Contains(","))
{
string[] split = line.Split(',');
if (split[row] == kill)
{
//achter split vul je de rij in
}
else
{
line = string.Join(",", split);
lines.Add(line);
}
}
}
}
using (StreamWriter writer = new StreamWriter(path, false))
{
foreach (string line in lines)
writer.WriteLine(line);
}
Assuming we ignore the subtleties of writing CSV, this should work:
public void RemoveColumnByIndex(string path, int index)
{
List<string> lines = new List<string>();
using (StreamReader reader = new StreamReader(path))
{
var line = reader.ReadLine();
List<string> values = new List<string>();
while(line != null)
{
values.Clear();
var cols = line.Split(',');
for (int i = 0; i < cols.Length; i++)
{
if (i != index)
values.Add(cols[i]);
}
var newLine = string.Join(",", values);
lines.Add(newLine);
line = reader.ReadLine();
}
}
using (StreamWriter writer = new StreamWriter(path, false))
{
foreach (var line in lines)
{
writer.WriteLine(line);
}
}
}
The code essentially loads each line, breaks it down into columns, loops through the columns ignoring the column in question, then puts the values back together into a line.
This is an over-simplified method, of course. I am sure there are more performant ways.
To remove the column by name, here is a little modification to your code example.
List<string> lines = new List<string>();
using (StreamReader reader = new StreamReader(System.IO.File.OpenRead(path)))
{
string target = "";//the name of the column to skip
int? targetPosition = null; //this will be the position of the column to remove if it is available in the csv file
string line;
List<string> collected = new List<string>();
while ((line = reader.ReadLine()) != null)
{
string[] split = line.Split(',');
collected.Clear();
//to get the position of the column to skip
for (int i = 0; i < split.Length; i++)
{
if (string.Equals(split[i], target, StringComparison.OrdinalIgnoreCase))
{
targetPosition = i;
break; //we've got what we need. exit loop
}
}
//iterate and skip the column position if exist
for (int i = 0; i < split.Length; i++)
{
if (targetPosition != null && i == targetPosition.Value) continue;
collected.Add(split[i]);
}
lines.Add(string.Join(",", collected));
}
}
using (StreamWriter writer = new StreamWriter(path, false))
{
foreach (string line in lines)
writer.WriteLine(line);
}
Related
the below code deleting the particular line like: line no 12
but exactly the need is keep the last 7000 lines and delete the remaining lines from the top of the txt.
string line = null;
int line_number = 0;
int line_to_delete = 12;
using (StreamReader reader = new StreamReader("C:\\input")) {
using (StreamWriter writer = new StreamWriter("C:\\output")) {
while ((line = reader.ReadLine()) != null) {
line_number++;
if (line_number == line_to_delete)
continue;
writer.WriteLine(line);
}
}
}
Something like this maybe?
var tempFile = Path.GetTempFileName();
var linesToKeep = File.ReadLines(fileName);
// if the file is less or equal than 7000, do nothing
if(linesToKeep.Count() > 7000) {
linesToKeep = linesToKeep.Skip(linesToKeep.Count() - 7000);
File.WriteAllLines(tempFile, linesToKeep);
File.Delete(fileName);
File.Move(tempFile, fileName);
}
Of course the 7000 can be substituted by something else like a variable.
Two passes of the file for low memory footprint.
int lines_to_keep = 7_000;
string line = null;
int line_number = 0;
int lines_in_file = 0;
using (StreamReader reader = new StreamReader("C:\\input")) {
while ((line = reader.ReadLine()) != null) {
lines_in_file++;
}
}
int lines_to_discard = lines_in_file - lines_to_keep
using (StreamReader reader = new StreamReader("C:\\input")) {
using (StreamWriter writer = new StreamWriter("C:\\output")) {
while ((line = reader.ReadLine()) != null && line_number < lines_to_discard) {
line_number ++
}
while ((line = reader.ReadLine()) != null) {
writer.WriteLine(line);
}
}
}
I want to compare two csv files and print the differences in a file. I currently use the code below to remove a row. Can I change this code so that it compares two csv files or is there a better way in c# to compare csv files?
List<string> lines = new List<string>();
using (StreamReader reader = new StreamReader(System.IO.File.OpenRead(path)))
{
string line;
while ((line = reader.ReadLine()) != null)
{
if (line.Contains(csvseperator))
{
string[] split = line.Split(Convert.ToChar(scheidingsteken));
if (split[selectedRow] == value)
{
}
else
{
line = string.Join(csvseperator, split);
lines.Add(line);
}
}
}
}
using (StreamWriter writer = new StreamWriter(path, false))
{
foreach (string line in lines)
writer.WriteLine(line);
}
}
Here is another way to find differences between CSV files, using Cinchoo ETL - an open source library
For the below sample CSV files
sample1.csv
id,name
1,Tom
2,Mark
3,Angie
sample2.csv
id,name
1,Tom
2,Mark
4,Lu
METHOD 1:
Using Cinchoo ETL, below code shows how to find differences between rows by all columns
var input1 = new ChoCSVReader("sample1.csv").WithFirstLineHeader().ToArray();
var input2 = new ChoCSVReader("sample2.csv").WithFirstLineHeader().ToArray();
using (var output = new ChoCSVWriter("sampleDiff.csv").WithFirstLineHeader())
{
output.Write(input1.OfType<ChoDynamicObject>().Except(input2.OfType<ChoDynamicObject>(), ChoDynamicObjectEqualityComparer.Default));
output.Write(input2.OfType<ChoDynamicObject>().Except(input1.OfType<ChoDynamicObject>(), ChoDynamicObjectEqualityComparer.Default));
}
sampleDiff.csv
id,name
3,Angie
4,Lu
Sample fiddle: https://dotnetfiddle.net/nwLeJ2
METHOD 2:
If you want to do the differences by id column,
var input1 = new ChoCSVReader("sample1.csv").WithFirstLineHeader().ToArray();
var input2 = new ChoCSVReader("sample2.csv").WithFirstLineHeader().ToArray();
using (var output = new ChoCSVWriter("sampleDiff.csv").WithFirstLineHeader())
{
output.Write(input1.OfType<ChoDynamicObject>().Except(input2.OfType<ChoDynamicObject>(), new ChoDynamicObjectEqualityComparer(new string[] { "id" })));
output.Write(input2.OfType<ChoDynamicObject>().Except(input1.OfType<ChoDynamicObject>(), new ChoDynamicObjectEqualityComparer(new string[] { "id" })));
}
Sample fiddle: https://dotnetfiddle.net/t6mmJW
If you only want to compare one column you can use this code:
List<string> lines = new List<string>();
List<string> lines2 = new List<string>();
try
{
StreamReader reader = new StreamReader(System.IO.File.OpenRead(pad));
StreamReader read = new StreamReader(System.IO.File.OpenRead(pad2));
string line;
string line2;
//With this you can change the cells you want to compair
int comp1 = 1;
int comp2 = 1;
while ((line = reader.ReadLine()) != null && (line2 = read.ReadLine()) != null)
{
string[] split = line.Split(Convert.ToChar(seperator));
string[] split2 = line2.Split(Convert.ToChar(seperator));
if (line.Contains(seperator) && line2.Contains(seperator))
{
if (split[comp1] != split2[comp2])
{
//It is not the same
}
else
{
//It is the same
}
}
}
reader.Dispose();
read.Dispose();
}
catch
{
}
I want to add a new column with checkbox, my data is from a csv file and showed it in a datagridview with this code:
DataTable dtDataSource = new DataTable();
string[] fileContent = File.ReadAllLines(\data.csv);
if (fileContent.Count() > 0)
{
//Create data table columns
dtDataSource.Columns.Add("ID);
dtDataSource.Columns.Add("Data 1");
dtDataSource.Columns.Add("Data 2");
dtDataSource.Columns.Add("Status");
//Add row data dynamically
for (int i = 1; i < fileContent.Count(); i++)
{
string[] rowData = fileContent[i].Split(',');
dtDataSource.Rows.Add(rowData);
}
if (dtDataSource != null)
{
dataGridView1.DataSource = dtDataSource;
}
}
But also I need to validate if checkbox is checked, the column ¨Status¨, their value must be changed by 1 or if is it unchecked the value must be 0 in every row of datagridview.
Example:
ID,Data1,Data2,Status,checkbox
1,aaa,bbb,0,✓
2,ccc,ddd,1,(unchecked)
3,eee,fff,1,(unchecked)
When you click the save button, the csv file should looks like this:
ID,Data1,Data2,Status
1,aaa,bbb,1
2,ccc,ddd,0
3,eee,fff,0
What I should do? Any ideas? CSV file is a little difficult for me.
Thank you!
I resolved this, thanks anyway..
This is the code:
string id;
for (int i = 0; i < dataGridView1.RowCount; i++) {
String path = "\\registros.csv";
List<String> lines = new List<String>();
if (File.Exists(path))
{
using (StreamReader reader = new StreamReader(path))
{
String line;
while ((line = reader.ReadLine()) != null)
{
id = (string)dataGridView1.Rows[i].Cells[2].Value;
if (line.Contains(","))
{
String[] split = line.Split(',');
if (split[1].Equals(id) && (bool)dataGridView1.Rows[i].Cells[0].FormattedValue == true)
{
split[10] = "" + 1;
line = String.Join(",", split);
}
if (split[1].Equals(id) && (bool)dataGridView1.Rows[i].Cells[0].FormattedValue == false)
{
split[10] = "" + 0;
line = String.Join(",", split);
}
}
lines.Add(line);
}
}
using (StreamWriter writer = new StreamWriter(path, false))
{
foreach (String line in lines)
writer.WriteLine(line);
}
}
}
I have a list of words. I want the program to scan for multiple words from a text file.
This is what i already have:
int counter = 0;
string line;
StringBuilder sb = new StringBuilder();
string[] words = { "var", "bob", "for", "example"};
try
{
using (StreamReader file = new StreamReader("test.txt"))
{
while ((line = file.ReadLine()) != null)
{
if (line.Contains(Convert.ToChar(words)))
{
sb.AppendLine(line.ToString());
}
}
}
listResults.Text += sb.ToString();
}
catch (Exception ex)
{
listResults.ForeColor = Color.Red;
listResults.Text = "---ERROR---";
}
So i want to scan the file for a word, and if it's not there, scan for the next word...
String.Contains() only takes one argument: a string. What your call to Contains(Convert.ToChar(words)) does, is probably not what you expect.
As explained in Using C# to check if string contains a string in string array, you might want to do something like this:
using (StreamReader file = new StreamReader("test.txt"))
{
while ((line = file.ReadLine()) != null)
{
foreach (string word in words)
{
if (line.Contains(word))
{
sb.AppendLine(line);
}
}
}
}
Or if you want to follow your exact problem statement ("scan the file for a word, and if it's not there, scan for the next word"), you might want to take a look at Return StreamReader to Beginning:
using (StreamReader file = new StreamReader("test.txt"))
{
foreach (string word in words)
{
while ((line = file.ReadLine()) != null)
{
if (line.Contains(word))
{
sb.AppendLine(line);
}
}
if (sb.Length == 0)
{
// Rewind file to prepare for next word
file.Position = 0;
file.DiscardBufferedData();
}
else
{
return sb.ToString();
}
}
}
But this will think "bob" is part of "bobcat". If you don't agree, see String compare C# - whole word match, and replace:
line.Contains(word)
with
string wordWithBoundaries = "\\b" + word + "\\b";
Regex.IsMatch(line, wordWithBoundaries);
StringBuilder sb = new StringBuilder();
string[] words = { "var", "bob", "for", "example" };
string[] file_lines = File.ReadAllLines("filepath");
for (int i = 0; i < file_lines.Length; i++)
{
string[] split_words = file_lines[i].Split(' ');
foreach (string str in split_words)
{
foreach (string word in words)
{
if (str == word)
{
sb.AppendLine(file_lines[i]);
}
}
}
}
This works a treat:
var query =
from line in System.IO.File.ReadLines("test.txt")
where words.Any(word => line.Contains(word))
select line;
To get these out as a single string, just do this:
var results = String.Join(Environment.NewLine, query);
Couldn't be much simpler.
If you want to match only whole words it becomes only a little more complicated. You can do this:
Regex[] regexs =
words
.Select(word => new Regex(String.Format(#"\b{0}\b", Regex.Escape(word))))
.ToArray();
var query =
from line in System.IO.File.ReadLines(fileName)
where regexs.Any(regex => regex.IsMatch(line))
select line;
How to start reading file from 2nd line skipping 1st line. This seems to work but is it best way to do so?
using (StreamReader sr = new StreamReader(varFile, Encoding.GetEncoding(1250))) {
string[] stringSeparator = new string[] { "\",\"" };
int i = 0;
while (!sr.EndOfStream) {
string line = sr.ReadLine(); //.Trim('"');
if (i > 0) {
string[] values = line.Split(stringSeparator, StringSplitOptions.None);
for (int index = 0; index < values.Length; index++) {
MessageBox.Show(values[index].Trim('"'));
}
}
i++;
}
}
If the file is not very large and can fit in memory:
foreach (var line in File.ReadAllLines(varFile, Encoding.GetEncoding(1250)).Skip(1))
{
string[] values = line.Split(',');
...
}
If not write an iterator:
public IEnumerable<string> ReadAllLines(string filename, Encoding encoding)
{
using (var reader = new StreamReader(filename, encoding))
{
string line;
while ((line = reader.ReadLine()) != null)
{
yield return line;
}
}
}
and then consume it:
foreach (var line in ReadAllLines(varFile, Encoding.GetEncoding(1250)).Skip(1))
{
string[] values = line.Split(',');
...
}
Could you not just read the first line outside of the loop without assigning it to a variable?
using (StreamReader sr = new StreamReader(varFile, Encoding.GetEncoding(1250))) {
string[] stringSeparator = new string[] { "\",\"" };
if (!sr.EndOfStream)
sr.ReadLine();
while (!sr.EndOfStream) {
string line = sr.ReadLine(); //.Trim('"');
string[] values = line.Split(stringSeparator, StringSplitOptions.None);
for (int index = 0; index < values.Length; index++) {
MessageBox.Show(values[index].Trim('"'));
}
}
}
I'm sorry but I see no problem with the way you are doing it though. I couldn't add comment.
So just for the sake of answering, you probably could have try to call ReadLine() once before the loop. Might not be the best way as I don't know whats the behavior of running ReadLine() if its already end of stream, but it nothing is gonna happen then thats gonna save you some checks.
Updated:
To give a more complete answer, calling ReadLine() when the stream is at its end will return a null.
Reference: http://msdn.microsoft.com/en-us/library/system.io.streamreader.readline.aspx
Remember to check the return for null value.