Python：使用for循环成对计算加速度

Question

这是一个示例数据集，其中包含来自 4 个不同行程的观察结果（有 4 个唯一的行程 ID）：

    trip_id                                time_interval    speed
0   8a8449635c10cc4b8e7841e517f27e2652c57ea3    873.96  0.062410
1   8a8449635c10cc4b8e7841e517f27e2652c57ea3    11.46   0.000000
2   8a8449635c10cc4b8e7841e517f27e2652c57ea3    903.96  0.247515
3   8a8449635c10cc4b8e7841e517f27e2652c57ea3    882.48  0.121376
4   8a8449635c10cc4b8e7841e517f27e2652c57ea3    918.78  0.185405
5   8a8449635c10cc4b8e7841e517f27e2652c57ea3    885.96  0.122147
6   f7fd70a8c14e43d8be91ef180e297d7195bbe9b0    276.60  0.583178
7   84d14618dcb30c28520cb679e867593c1d29213e    903.48  0.193313
8   84d14618dcb30c28520cb679e867593c1d29213e    899.34  0.085377
9   84d14618dcb30c28520cb679e867593c1d29213e    893.46  0.092259
10  84d14618dcb30c28520cb679e867593c1d29213e    849.36  0.350341
11  3db35f9835db3fe550de194b55b3a90a6c1ecb97    10.86   0.000000
12  3db35f9835db3fe550de194b55b3a90a6c1ecb97    919.50  0.071119

我正在尝试计算从一个点到另一个点的每个独特行程的加速度。

示例：

将使用第 0 行和第 1 行（0 初始值；1 最终值）计算第一个加速度值
将使用第 1 行和第 2 行（1 个初始值；2 个最终值）计算第二个加速度值
...等等。

因为我想根据 trip_id 为每个单独的行程计算这个，这就是我尝试的：

def get_acceleration(dataset):
    
    ##### INITIALISATION VARIABLES #####
    # Empty string for the trip ID
    current_trip_id = ""
    
    # Copy of the dataframe
    dataset2 = dataset.copy()
    
    # Creating a new column for the acceleration between observations of the same trip
    # all rows have a default value of 0
    dataset2["acceleration"] = 0
    
    ##### LOOP #####
    for index,row in dataset.iterrows():
        
        # Checking if we are looking at the same trip
        # when looking at the same trip, the default values of zero are replaced
        # by the calculated trip characteristic
        if row["trip_id"] == current_trip_id:
            
            # Final speed and time
            final_speed = row["speed"]
            final_time = row["time_interval"]
            
            print(type(final_speed))
                      
            # Computing the acceleration (delta_v/ delta_t)
            acceleration = (final_speed[1] - initial_speed[0])/(final_time[1] - initial_time[0])
            
            # Adding the output to the acceleration column
            dataset2.loc[index, "acceleration"] = acceleration
        
        ##### UPDATING THE LOOP #####
        current_trip_id = row["trip_id"]
        
        # Initial speed and time
        initial_speed = row["speed"]
        initial_time = row["time_interval"]
        
    return dataset2

但是，我收到错误消息：


<ipython-input-42-0255a952850b> in get_acceleration(dataset)
     27 
     28             # Computing the acceleration (delta_v/ delta_t)
---> 29             acceleration = (final_speed[1] - initial_speed[0])/(final_time[1] - initial_time[0])
     30 
     31             # Adding the output to the acceleration column

TypeError: 'float' object is not subscriptable

如何解决这个错误并计算加速度？

更新：

使用下面的答案后，为了避免被零除，只需添加一个 if 和 else 语句。

            delta_speed = final_speed - initial_speed
            delta_time = final_time - initial_time
            
            # Computing the acceleration (delta_v/ delta_t)
            if delta_time != 0:
                acceleration = (delta_speed)/(delta_time)
            
            else:
                acceleration = 0

Answer 1

有效

acceleration = (final_speed - initial_speed)/(final_time - initial_time)

	trip_id	time_interval	speed	acceleration
0	8a8449635c10cc4b8e7841e517f27e2652c57ea3	873.96	0.062410	0.000000
1	8a8449635c10cc4b8e7841e517f27e2652c57ea3	11.46	0.000000	0.000072
2	8a8449635c10cc4b8e7841e517f27e2652c57ea3	903.96	0.247515	0.000277
3	8a8449635c10cc4b8e7841e517f27e2652c57ea3	882.48	0.121376	0.005872
4	8a8449635c10cc4b8e7841e517f27e2652c57ea3	918.78	0.185405	0.001764
5	8a8449635c10cc4b8e7841e517f27e2652c57ea3	885.96	0.122147	0.001927
6	f7fd70a8c14e43d8be91ef180e297d7195bbe9b0	276.60	0.583178	0.000000
7	84d14618dcb30c28520cb679e867593c1d29213e	903.48	0.193313	0.000000
8	84d14618dcb30c28520cb679e867593c1d29213e	899.34	0.085377	0.026071
9	84d14618dcb30c28520cb679e867593c1d29213e	893.46	0.092259	0.001170
10	84d14618dcb30c28520cb679e867593c1d29213e	849.36	0.350341	-0.005852
11	3db35f9835db3fe550de194b55b3a90a6c1ecb97	10.86	0.000000	0.000000
12	3db35f9835db3fe550de194b55b3a90a6c1ecb97	919.50	0.071119	0.000078

Python：使用for循环成对计算加速度

Python: Pairwise computation of acceleration using for loop

python

for-loop

if-statement

pandas

pairwise