构造函数的 DataFrame 错误未正确调用答案

【问题标题】：DataFrame error of constructor not properly called构造函数的 DataFrame 错误未正确调用
【发布时间】：2021-06-04 19:42:26
【问题描述】：

所以我有一个使用我的代码创建的数据框，当我使用 for 循环进行循环时通过列并获得不同的结果以创建另一个数据框我得到这个错误 DataFrame 构造函数没有正确调用！

这是我的代码

#get all trafficlights ids with traci
tlsID= traci.trafficlight.getIDList()
print(tlsID)

# loop through the trafficlights ids and save them to dataframe
for i in tlsID:
    df = pd.DataFrame(tlsID, columns=[i])
    i =+1

# remane the coulmn to any name you want
df.columns= ['tlsID']

# export your dataframe to csv file
df.to_csv('tlsID.csv', index=False)

# convert dataframe to strings
tlsID_df= df['tlsID'].astype(str)

# create an empty list to append new items to it
df3=[]
df4=[]
# loop through your dataframe
for i in tlsID_df:
    # get all lanes controlled by trafficlights (incoming lanes)and append to your list
    controlled_lanes= traci.trafficlight.getControlledLanes(i)
    appended = pd.DataFrame(controlled_lanes)
    df3.append(appended)
    i =+1

# put a name your column to use it later
col1= ['incoming']

# transfer your list to a dataframe
lanes= pd.concat(df3, ignore_index= True)

# remane your column
lanes.columns= col1

# drop duplicated rows
lanes= lanes.drop_duplicates()

# reset your index
lanes = lanes.reset_index(drop=True)
lanes.to_csv('incoming_links.csv', index=False)

lanes_df= lanes['incoming'].astype(str)
for i in lanes_df:
    # get all lanes controlled by trafficlights (incoming lanes)and append to your list
    lane= traci.lane.getLength(i)
    append = pd.DataFrame(lane)
    df4.append(append)
    i =+1
# put a name your column to use it later
col2= ['len']

# transfer your list to a dataframe
lanes_len= pd.concat(df4, ignore_index= True)

# remane your column
lanes_len.columns= col2

# drop duplicated rows
lanes_len= lanes_len.drop_duplicates()

# reset your index
lanes_len = lanes_len.reset_index(drop=True)

# export your dataframe to csv file
lanes_len.to_csv('lanes_len.csv', index=False)

我的错误出现在第二个 for 循环中

for i in lanes_df:
    # get all lanes controlled by trafficlights (incoming lanes)and append to your list
    lane= traci.lane.getLength(i)
    append = pd.DataFrame(lane)
    df4.append(append)
    i =+1

这个函数 - traci.lane.getLength(i) - 返回浮点数

可能是什么问题，因为我之前已经使用过它并且效果很好

【问题讨论】：

标签： python pandas dataframe csv for-loop

【解决方案1】：

所以我想通了，问题是我的代码返回浮点数，我无法用浮点数创建数据帧

所以我这样做了

for i in lanes_df:
    # get all lanes controlled by trafficlights (incoming lanes)and append to your list
    lane= traci.lane.getLength(i)
    append = df4.append(lane)    

    i =+1

lanes_len = pd.DataFrame(np.array([df4]).T)
lanes_len.columns= ['len']

我首先将所有值附加到我的列表中，然后使用 numpy 数组创建我的数据框（注意我使用转置将每个值附加到单独的行中）

【讨论】：