将具有字符串节点标签的边列表映射到整数标签

问题描述

我有一个边缘列表格式的巨大图形，其中字符串作为节点标签.我想知道将字符串映射到整数的最佳"方法是什么.输入文件遵循以下示例:

I have a huge graph in edgelist format with strings as node labels. I wonder what is the "best" way to map strings to integers. Input file follows the example:

Mike Andrew
Mike Jane
John Jane

输出(即映射文件)应为:

The output (i.e., a mapped file) should be:

1 2
1 3
4 3

下面粘贴的是C语言中的框架，该框架读取输入文件.有人可以建议我该怎么做.

Pasted below is a skeleton in C that reads the input file. Could somebody please advice me how to proceed.

#include <stdio.h>

int LoadFile(const char * filename) {
  FILE *fp = NULL;
  char node1[10];
  char node2[10];
  int idx = 0;

  fp = fopen(filename, "r");
  if (fp == NULL) {
    perror("Error");
  }

  while (fscanf(fp, "%s %s", &node1, &node2) == 2) {
    idx++;
  }

  fclose(fp);

  return idx;
}

int main(void) {
  int n = LoadFile("./test.txt");
  printf("Number of edges: %d\n", n);
  return 0;
}

推荐答案

您需要天真的地图实现(将字符串映射为整数).

• 定义如下的结构以存储字符串.

• Define a structure as below to store the strings.

    typedef struct {
       unsigned int hashed;
       char **map;
   } hash;

定义一个函数，该函数将在字符串不存在的情况下将其插入到哈希图中，并返回哈希图中的字符串索引.

Define a function which will insert the string into hashmap if it is not exists and return the index of string in hashmap.

int insertInMap(hash *map, char *entry)

将返回的索引存储到edge结构中.

Store the returned index into edge structure.

edges[i].first =insertInMap(&map,first_string); edges[i].second =insertInMap(&map,second_string)

edges[i].first =insertInMap(&map,first_string); edges[i].second =insertInMap(&map,second_string)

示例代码:

typedef struct {
    unsigned int first;
    unsigned int second;
} edge;

typedef struct {
    unsigned int hashed;
     char **map;
} hash;


int insertInMap(hash *map, char *entry)
{
  int i =0;
  for (i=0;i<map->hashed;i++)
  {
    if (strcmp(map->map[i],entry) == 0)
    return i+1;
  }
  /* Warning no boundary check is added */
  map->map[map->hashed++] = strdup(entry);
  return map->hashed;
}


edge *LoadFile(const char * filename) {
  FILE *fp = NULL;
  char node1[10];
  char node2[10];
  int idx = 0;

  edge *edges;
  hash map;

  int numEdges = 10;
  edges = malloc( numEdges * sizeof(edge));

  map.map = malloc(numEdges * sizeof(char*));
  map.hashed = 0;

  fp = fopen(filename, "r");
  if (fp == NULL) {
    perror("Error");
  }

  while (fscanf(fp, "%s %s", &node1, &node2) == 2) {
    if (idx >= numEdges)
    {
         numEdges *=2;
         edges = realloc(edges, numEdges * sizeof(edge));

         map.map = realloc(map.map, numEdges * sizeof(char*));
    }
    edges[idx].first =insertInMap(&map,node1);
    edges[idx].second =insertInMap(&map,node2);
    idx++;
  }

  fclose(fp);

  return edges;
}

稍后打印edges.

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