In Python, we can use collections.deque to implement FIFO queue operations. For example:

from collections import deque
queue = deque([1, 2, 3])
print("Initial queue:", queue) # Output: deque([1, 2, 3])
first_element = queue.popleft() 
print("Popped element:", first_element) # Output: 1
print("Current queue:", queue) # Output: deque([2, 3])

The code implement the following functionality:

• Create a queue and initialize with elements
• Remove/return the first element (FIFO)
• Check the current queue state I would like to know how to implement similar queue functionality in DolphinDB. I tried using vectors with the following approach:

queue = [1, 2, 3]
firstElement = queue[0] // Attempt to pop the first element
queue = erase(queue, 0) // Attempt to delete element at index 0

However this trigger an error:

Syntax Error: [line #3] Cannot recognize the token erase

The DolphinDB document( https://docs.dolphindb.com/en/Functions/e/erase!.html ) mentions erase, but I am encountering syntax errors.

What is the correct way to implement a FIFO queue in DolphinDB?

• Is there a built-in queue structure?

• If not, how can I simulate popleft() and append() operations?

Thanks in advance for your help!

In Python, we can use collections.deque to implement FIFO queue operations. For example:

from collections import deque
queue = deque([1, 2, 3])
print("Initial queue:", queue) # Output: deque([1, 2, 3])
first_element = queue.popleft() 
print("Popped element:", first_element) # Output: 1
print("Current queue:", queue) # Output: deque([2, 3])

The code implement the following functionality:

• Create a queue and initialize with elements
• Remove/return the first element (FIFO)
• Check the current queue state

I would like to know how to implement similar queue functionality in DolphinDB. I tried using vectors with the following approach:

queue = [1, 2, 3]
firstElement = queue[0] // Attempt to pop the first element
queue = erase(queue, 0) // Attempt to delete element at index 0

However this trigger an error:

Syntax Error: [line #3] Cannot recognize the token erase

The DolphinDB document( https://docs.dolphindb.com/en/Functions/e/erase!.html ) mentions erase, but I am encountering syntax errors.

What is the correct way to implement a FIFO queue in DolphinDB?

• Is there a built-in queue structure?

• If not, how can I simulate popleft() and append() operations?

Thanks in advance for your help!