为什么float（）无法将字符串转换为float？

Question

我的程序试图将字符串从字符串列表转换为浮点数时出错。从CSV文本文件中的一行读取列表，然后将其分离为一个列表。我该怎么做？为什么会出错？下面是相关的代码位：

def Main():
    srcf = open(bkp, 'r')
    for line in srcf:
        liLn = line.split(',')

…然后调用以下函数。。。

def Pred_PSME(liLn):
    dbh = float(liLn[6])

这是文件中的一行：

1345327,20486,"ABCO","Abies concolor","Y","Y","31.496","0.0779","19.3567",,"0.5602","0",1,"0.9268","11.8968","2.6832","6.6646","2399.256",54.47,24.15,248.47,42.19,9.16,8.16,9.23,272.27,264.11,369.30,345.15,71.80,0.00,0.00,4393.57,4106.22,3239.25,3142.07,854.30,0.00,0.00,,12.70,10.16,15.24,0.02,0.04,0.38,0.38,0.00,0.00,1.95,1.83,1.44,1.40

我收到此错误消息：

Traceback (most recent call last):  
  File "/home/cfws/python/error_calcs/FC_NF_PredInt_Gen8.py", line 263, in <module>  
    Main()  
  File "/home/cfws/python/error_calcs/FC_NF_PredInt_Gen8.py", line 36, in Main  
    li_tBQI = BQI_Calc(liLn)  
  File "/home/cfws/python/error_calcs/FC_NF_PredInt_Gen8.py", line 63, in BQI_Calc  
    di_eqns = {"PSME": Pred_PSME(liLn), "ABAM":Pred_ABAM(liLn), \  
  File "/home/cfws/python/error_calcs/FC_NF_PredInt_Gen8.py", line 172, in Pred_PSME  
    dbh = float(liLn[6])  
ValueError: could not convert string to float: "31.496"

我在Ubuntu Linux计算机上使用Python 2.7。

Answer 1

你需要去掉字符串上的双引号。然后，您将给出float（）可以转换的合法浮点字符串。