# How to speed up about loading CSV file?

**URL:** https://discourse.vtk.org/t/how-to-speed-up-about-loading-csv-file/1111
**Category:** Support
**Created:** [June 11, 2019, 2:49am UTC](https://discourse.vtk.org/t/how-to-speed-up-about-loading-csv-file/1111 "2019-06-11T02:49:49Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![Kim\_William](https://discourse.vtk.org/user_avatar/discourse.vtk.org/kim_william/32/373_2.png) [@Kim\_William](https://discourse.vtk.org/u/Kim_William)
#### Post date: [June 11, 2019, 2:49am UTC](https://discourse.vtk.org/t/how-to-speed-up-about-loading-csv-file/1111/1 "2019-06-11T02:49:49Z")

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Hi all!

I have a question about loading the CSV file.

I’m using the ‘vtkDelimitedTextReader’ class to read the CSV model file.

The code is as below:

```
vtkNew<vtkDelimitedTextReader> m_vtkCSVReader;

m_vtkCSVReader->SetFileName(path);
m_vtkCSVReader->DetectNumericColumnsOn();
m_vtkCSVReader->SetFieldDelimiterCharacters(",");
m_vtkCSVReader->Update();

vtkSmartPointer<vtkTable> table = m_vtkCSVReader->GetOutput();

vtkNew<vtkPoints> points;

int row = table->GetNumberOfRows();
int col = table->GetNumberOfColumns();

for (vtkIdType i = 0; i < table->GetNumberOfRows(); i++)
{
	points->InsertNextPoint((table->GetValue(i, 0)).ToDouble(),
		(table->GetValue(i, 1)).ToDouble(),
		(table->GetValue(i, 2)).ToDouble());
}

vtkNew<vtkPolyData> polydata;
polydata->SetPoints(points);

vtkNew<vtkVertexGlyphFilter> glyphFilter;
glyphFilter->SetInputData(polydata);
glyphFilter->Update();

vtkNew<vtkLookupTable> lut;
double minz = 0.0f, maxz = 0.0f;
GetDataBounds(polydata, &minz, &maxz);

int numPoints = points->GetNumberOfPoints();
CreateLookupTable(minz, maxz, numPoints, &lut);

vtkNew<vtkUnsignedCharArray> colors;
CreateScalars(points, lut, &colors);

polydata->GetPointData()->SetScalars(colors);

vtkNew<vtkPointGaussianMapper> mapper;
mapper->SetInputConnection(glyphFilter->GetOutputPort());
mapper->EmissiveOff();
mapper->SetScaleFactor(0);

vtkNew<vtkActor> actor;
actor->SetMapper(mapper);
actor->GetProperty()->SetOpacity(1.0);

vtkNew<vtkRenderer> renderer;
renderer->AddActor(actor);
renderer->SetBackground(.1, .2, .3);
renderer->ResetCamera();

vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
renderWindowInteractor->SetRenderWindow(m_vtkRenderWindow);
renderWindowInteractor->Initialize();

vtkNew<CCustomMouseInteractorStyle> style;
style->SetDefaultRenderer(renderer);
style->SetParent(this);
renderWindowInteractor->SetInteractorStyle(style);
renderWindowInteractor->Initialize();

m_vtkRenderWindow->AddRenderer(renderer);
m_vtkRenderWindow->Render();

```

It works well but the speed is very slow.  
Is there any fast way of reading the CSV model file?

Could you please advise me? 😭

Thank you 🙂

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<div class="post-metadata">

### Author: ![utkarshayachit](https://discourse.vtk.org/user_avatar/discourse.vtk.org/utkarshayachit/32/379_2.png) [@utkarshayachit](https://discourse.vtk.org/u/utkarshayachit)
#### Post date: [June 11, 2019, 1:50pm UTC](https://discourse.vtk.org/t/how-to-speed-up-about-loading-csv-file/1111/2 "2019-06-11T13:50:55Z")

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I’d recommend timing individual components using `vtkTimerLog`. Is the `m_vtkCSVReader->Update()` the slow part or is the filling up of `vtkPoints`?

If it’s the filling up of `vtkPoints`, here are ways to improve it:

1. use `Allocate` to avoid resizing array on each `InsertNextPoint`. e.g. `points->Allocate(table->GetNumberOfRows())` before the for loop.
2. Don’t use `vtkTable::GetValue` is has unncessary conversions to `vtkVariant`. Directly access the column array and use them. e.g.

```auto
auto xArray = vtkDoubleArray::SafeDownCast(table->GetColumn(0));
auto yArray = vtkDoubleArray::SafeDownCast(table->GetColumn(1));
auto zArray = vtkDoubleArray::SafeDownCast(table->GetColumn(2));
for (...)
{
   points->InsertNextPoint(xArray->GetTypedComponent(i, 0), 
                           yArray->GetTypedComponent(i, 0), 
                           zArray->GetTypedComponent(i, 0));

}

```

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<div class="post-metadata">

### Author: ![Kim\_William](https://discourse.vtk.org/user_avatar/discourse.vtk.org/kim_william/32/373_2.png) [@Kim\_William](https://discourse.vtk.org/u/Kim_William)
#### Post date: [June 12, 2019, 2:37am UTC](https://discourse.vtk.org/t/how-to-speed-up-about-loading-csv-file/1111/3 "2019-06-12T02:37:29Z")

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Thank you for your reply!

I found that the `m_vtkCSVReader->Update()` is the slow part.