[英]List index out of range while sorting in python
我正在嘗試將CSV文件讀取到列表中,然后根據列表的前兩列對其進行排序(如果第一列相同,則按第一列,然后按第二列)。 這就是我在做什么:
def sortcsvfiles(inputfilename,outputfilename):
list1=[]
row1=[]
with open(inputfilename,'rt') as csvfile1:
reader=csv.reader(csvfile1)
cnt=0
for row in reader:
if cnt==0: #skip first row as it contains header information
row1=row
cnt+=1
continue
list1.append((row))
list1.sort(key=lambda ro: (int(ro[0]),int(ro[1])))
list1.insert(0, row1)
with open(outputfilename,'wt') as csvfile1:
writer=csv.writer(csvfile1, lineterminator='\n')
for row in list1:
writer.writerow(row)
但是我收到以下錯誤:
File "C:\Users\50004182\Documents\temp.py", line 37, in <lambda>
list1.sort(key=lambda ro: (int(ro[0]),int(ro[1])))
IndexError: list index out of range
我怎樣才能解決這個問題?
您的文件中可能有一個空行。 也許是最后一個。 例如,您可以忽略空行:
def sortcsvfiles(inputfilename,outputfilename):
with open(inputfilename,'rt') as csvfile:
reader = csv.reader(csvfile)
header = next(reader)
data = [row for row in reader if row] # ignore empty lines
data.sort(key=lambda ro: (int(ro[0]),int(ro[1])))
with open(outputfilename,'wt') as csvfile:
writer=csv.writer(csvfile, lineterminator='\n')
writer.writerow(header)
writer.writerows(data)
發生錯誤是因為您至少有一行沒有2列。 它可能有1甚至0。
您可以在添加行之前對此進行測試:
if len(row) > 1:
list1.append(row)
要對所有行進行排序,但跳過第一個標頭,可以使用next()
函數(請參見mine的先前答案 ); 使用sorted()
函數也許:
def sortcsvfiles(inputfilename, outputfilename):
with open(inputfilename,'rt') as csvfile1:
reader = csv.reader(csvfile1)
headers = next(reader, None) # get one row, or None if there are no rows
rows = sorted(
(r for r in reader if len(r) > 1),
key=lambda r: (int(r[0]), int(r[1])))
with open(outputfilename,'wt') as csvfile1:
writer = csv.writer(csvfile1, lineterminator='\n')
if headers:
writer.writerow(headers)
writer.writerows(rows)
我使用writer.writerows()
在一次調用中寫入了排序行的整個列表。
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