如何用Python将含3列的文本文件转换为嵌套字典形式的图

Got it, let's turn that text file into the nested dictionary graph you're after. Here's a clean, straightforward approach in Python that handles both file input and direct string data if you don't want to use a file.

Option 1: Read from a Text File #

If your data is stored in a .txt file (let's call it graph_data.txt), use this code:

# Initialize empty graph dictionary
graph = {}

# Open and read the file (replace 'graph_data.txt' with your actual file path)
with open('graph_data.txt', 'r') as file:
    # Skip the header line so we don't process it as node data
    next(file)
    # Process each line in the file
    for line in file:
        # Strip whitespace and split the line into node and weight components
        from_node, to_node, weight = line.strip().split()
        # Convert weight from string to integer
        weight = int(weight)
        # Add the edge to the graph: create a sub-dict for the from_node if it doesn't exist
        if from_node not in graph:
            graph[from_node] = {}
        graph[from_node][to_node] = weight

# Verify the result (optional)
print(graph)

Option 2: Use Direct String Data #

If you have the data as a string (instead of a file), you can process it directly like this:

# Your graph data as a multi-line string
graph_data = """#FromNodeId ToNodeId Weight
B A 5
B D 1
B G 2
A B 5
A D 3
A E 12
A F 5
D B 1
D G 1
D E 1
D A 3
G B 2
G D 1
G C 2
C G 2
C E 1
C F 16
E A 12
E D 1
E C 1
E F 2
F A 5
F E 2
F C 16"""

graph = {}
# Split the string into individual lines
lines = graph_data.strip().split('\n')
# Skip the first header line
for line in lines[1:]:
    from_node, to_node, weight = line.strip().split()
    weight = int(weight)
    # Build the nested dictionary structure
    if from_node not in graph:
        graph[from_node] = {}
    graph[from_node][to_node] = weight

# Check the output
print(graph)

How It Works #

• Skipping the Header: Both methods skip the first line (#FromNodeId ToNodeId Weight) since it's just metadata, not actual graph edges.
• Processing Each Line: Each line is split into three parts: the starting node, target node, and weight. The weight gets converted to an integer because file/string input reads it as text by default.
• Building the Nested Dict: For each starting node, we check if it's already in the main graph dict. If not, we create an empty sub-dictionary for it. Then we add the target node and its corresponding weight to that sub-dictionary.

Running either code will produce exactly the nested dictionary structure you specified.

内容的提问来源于stack exchange，提问作者Vinil Thombrey