Question

我正在RStudio工作。我有一个名为“ X12_5_3”的Excel文件中的数据：

    P,     1,    2,    3
 5350,    17,   44,   50
25831,   788,  890, 1409
 5594,   968,  218,  344
10359,   212,  185,  306

我想创建一个名为weight的新列，并为前两行添加值0.4，为后两行添加值0.6。

我目前的代码是：

data<- X12_5_3

Answer 1

这是一个建议的解决方案：

按参考设置基本数据框：

X12_5_3 <-data.frame（“ P” = c（5350，25831，5594，10359）， “ 1” = c（17,788,968,212）， “ 2” = c（44,890,218,185）， “ 3” = c（50，1409，344，306））
根据4个值的向量创建数据框

权重<-data.frame（c（0.4，0.4，0.6，0.6））
在数据的最后一列之后将两个数据帧与cbind()绑定在一起

X12_5_3 <-cbind（X12_5_3，重量）
使用colnames
重命名列
colnames（X12_5_3）<-c（“ P”，“ 1”，“ 2”，“ 3”，“重量”）
查看更新的数据框：

X12_5_3

这将显示带有添加的列数据的名为X12_5_3的数据框。

控制台输出：

> X12_5_3 <- data.frame( "P" = c(5350, 25831, 5594, 10359),
+                        "1" = c(17,788,968,212),
+                        "2" = c(44,890,218,185),
+                        "3" = c(50, 1409, 344, 306) )
> 
> weight <- data.frame( c( 0.4, 0.4, 0.6, 0.6))
> 
> X12_5_3 <- cbind(X12_5_3, weight)  
> colnames(X12_5_3) <- c("P", "1", "2", "3", "weight")    
> 
> X12_5_3
      P   1   2    3 weight
1  5350  17  44   50    0.4
2 25831 788 890 1409    0.4
3  5594 968 218  344    0.6
4 10359 212 185  306    0.6

Answer 2

typedef struct beer_data 
{
    char name[20]; //names
    int id; //ID number given to beer
    int quantity; //stock
    float price; // pricing
} beer_data;

void search_by_name(beer_data *beers, int total)
{
    char buf[20];
    printf("Enter name to search: ");
    scanf("%19s", buf);
    //note, we put %19s because beers[count].name is only 20 bytes long

    for(int i = 0; i < total; i++)
    {
        if(strcmp(beers[i].name, buf) == 0)
        {
            printf("Found: %s, %d, %d, %.2f\n",
                beers[i].name, beers[i].id, beers[i].quantity, beers[i].price);
            return;
        }
    }
    printf("%s not found\n", buf);
}

void print_list(beer_data *beers, int total)
{
    for(int i = 0; i < total; i++)
    {
        printf("%s %d %d %.2f\n",
            beers[i].name, beers[i].id, beers[i].quantity, beers[i].price);
    }
}

void add_item(beer_data *beers, int *total)
{
    //note, total has to be passed as pointer 
    //because we are changing it

    //allocate more memory:
    beers = realloc(beers, sizeof(beer_data) * (*total + 1));

    printf("enter name: "); 
    scanf("%19s", beers[*total].name);

    printf("enter id:");
    scanf("%d", &beers[*total].id);

    printf("enter quantity:");
    scanf("%d", &beers[*total].quantity);

    printf("enter price:");
    scanf("%f", &beers[*total].price);

    //increase the total
    *total += 1;
}

int main() 
{
    FILE *fp = fopen("beer.dat", "r");
    if(!fp)
    {
        printf("Error: can't open file to read\n");
        return 0;
    }

    char buf[500];

    int maximum = 0;
    fscanf(fp, "%d", &maximum);

    //read the rest of the line and discard it 
    fgets(buf, sizeof(buf), fp);

    //allocate memory
    beer_data *beers = malloc(maximum * sizeof(beer_data));

    int total = 0;
    while(1)
    {
        fgets(buf, sizeof(buf), fp);
        sscanf(buf, "%19s", beers[total].name);

        if(fscanf(fp, "%d", &beers[total].id) != 1) break;
        fgets(buf, sizeof(buf), fp);

        if(fscanf(fp, "%d", &beers[total].quantity) != 1) break;
        fgets(buf, sizeof(buf), fp);

        if(fscanf(fp, "%f", &beers[total].price) != 1) break;
        fgets(buf, sizeof(buf), fp);

        total++;
        if(total == maximum)
            break;
    }

    fclose(fp);

    int stop = 0;
    while (!stop)
    {
        printf("\
    Enter 0 to exit\n\
    Enter 1 print list\n\
    Enter 2 for search\n\
    Enter 3 add new item\n");

        int choice;
        scanf("%d", &choice);
        switch(choice)
        {
        case 0: 
            stop = 1;
            break;

        case 1:
            print_list(beers, total);
            break;

        case 2:
            search_by_name(beers, total);
            break;

        case 3:
            add_item(beers, &total);
            break;
        }
        printf("\n");
    }

    //cleanup:
    free(beers);

    return 0;
}

向数据添加新列（来自Excel文件）

2 个答案:

控制台输出：