Frequently Asked Questions

Why does my pip complain package not found when installing Taichi?

You may have a Python interpreter with an unsupported version. Currently, Taichi only supports Python 3.6/3.7/3.8 (64-bit) . For more information about installation related issues, please check Installation Troubleshooting.

Does Taichi provide built-in constants such as ti.pi?

There is no built-in constant such as pi. We recommended using math.pi directly.

Outer-most loops in Taichi kernels are by default parallel. How can I serialize one of them?

A solution is to add an additional ghost loop with only one iteration outside the loop you want to serialize.

for _ in range(1):  # This "ghost" loop will be "parallelized", but with only one thread. Therefore, the containing loop below is serialized.
    for i in range(100):  # The loop you want to serialize
        ...

What is the most convenient way to load images into Taichi fields?

One feasible solution is field.from_numpy(ti.tools.imread('filename.png')).

Can Taichi interact with other Python packages such as matplotlib?

Yes, Taichi supports many popular Python packages. Taichi provides helper functions such as from_numpy and to_numpy to transfer data between Taichi fields and NumPy arrays, so that you can also use your favorite Python packages (e.g., numpy, pytorch, matplotlib) together with Taichi as below:

import taichi as ti
pixels = ti.field(ti.f32, (1024, 512))
import numpy as np
arr = np.random.rand(1024, 512)
pixels.from_numpy(arr)   # load numpy data into taichi fields
import matplotlib.pyplot as plt
arr = pixels.to_numpy()  # store taichi data into numpy arrays
plt.imshow(arr)
plt.show()
import matplotlib.cm as cm
cmap = cm.get_cmap('magma')
gui = ti.GUI('Color map')
while gui.running:
    render_pixels()
    arr = pixels.to_numpy()
    gui.set_image(cmap(arr))
    gui.show()

Besides, you can also pass numpy arrays or torch tensors into a Taichi kernel as arguments. See Interacting with external arrays for more details.

How do I declare a field with a dynamic length?

The dynamic SNode supports variable-length fields. It acts similarly to std::vector in C++ or list in Python.

tip

An alternative solution is to allocate a large enough dense field, with a corresponding 0-D field field_len[None] tracking its length. In practice, programs allocating memory using dynamic SNodes may be less efficient than using dense SNodes, due to dynamic data structure maintainance overheads.

How do I program on less structured data structures (such as graphs and tetrahedral meshes) in Taichi?

These structures have to be decomposed into 1D Taichi fields. For example, when representing a graph, you can allocate two fields, one for the vertices and the other for the edges. You can then traverse the elements using for v in vertices or for v in range(n).