的代码：

Question

我有一个从CSV文件中读取的python脚本，并检查记录是否符合条件。

如果是，则系统显示结果
如果没有系统根据错误引发异常。

csv文件包含浮点值的字段，但其中一些记录可能没有任何值，因此将为空。

问题是如果单元格为空，系统会显示此ValueError：

could not convert string to float:

而不是我写的异常。

 raise Exception("this Record has empty value")

行[0] ==＆GT;日期类型日期
行[10] ==＆GT;风速型浮球
行[11] ==＆GT;雾型布尔

的代码：

import csv

mydelimeter = csv.excel()
mydelimeter.delimiter=";"
myfile = open("C:/Users/test/Documents/R_projects/homework/rdu-weather-history.csv")

# read the first line in the opened file ==> Header
myfile.readline()


myreader=csv.reader(myfile,mydelimeter)
mywind,mydate=[],[]
minTemp, maxTemp = [],[]
fastwindspeed, fog=[],[]

'''
create a variable that handle values of the 3 fields ==> Date - fastest5secwindspeed - fog
 and display the result where  
     fog ==> Yes    and highest speed  more than 10.
'''
for row in myreader:
    try:
        if row[11] =="Yes":
            if float(row[10]) < 10.0:
                raise Exception( 'the wind speed  is below 10 mph in ' + row[0] )
            if row[10] in (None, ""):
                raise Exception("this Record has empty value")

            print(row[0],row[10],row[11])
    except Exception as e:
        print("{}".format(e))

myfile.close()

Answer 1

您可以更改加注的顺序，也应该在该列中处理非浮动的可能性：

import csv

mydelimeter = csv.excel()
mydelimeter.delimiter=";"
myfile = open("C:/Users/test/Documents/R_projects/homework/rdu-weather-history.csv")

# read the first line in the opened file ==> Header
myfile.readline()


myreader=csv.reader(myfile,mydelimeter)
mywind,mydate=[],[]
minTemp, maxTemp = [],[]
fastwindspeed, fog=[],[]

'''
create a variable that handle values of the 3 fields ==> Date - fastest5secwindspeed - fog
 and display the result where  
     fog ==> Yes    and highest speed  more than 10.
'''
for row in myreader:
    try:
        if row[11] =="Yes":
            if row[10] in (None, ""):
                raise Exception("this Record has empty value")
            try:
                if float(row[10]) < 10.0:
                    raise Exception( 'the wind speed  is below 10 mph in ' + row[0] )
            except ValueError:
                raise Exception('This Column expected to have a float has a non-float instead")

            print(row[0],row[10],row[11])
    except Exception as e:
        print("{}".format(e))

myfile.close()

Answer 2

我在项目工作期间也遇到过这个问题。我刚刚在下面做了： -

  if(len(row[10]) > 0):
      wind_speed = flot(row[10])

如何修复ValueError：无法将字符串转换为float：在Python中

的代码：

2 个答案: