CSV文件行遞增

Question

目前我正在處理一個CSV文件程序，我必須將CSV文件分割成不重疊的部分（按行），但不應在磁盤中創建任何額外的文件。

目前我使用這個程序來讀取CSV文件中按行的特定部分：

def dataFromFile(fname): 
    record = [] 
    count=0 
    with open(fname, 'rb') as f: 
     reader = csv.reader(f) 
     for row in reader: 
      while '' in row: 
        row.remove('') 
      count+=1 
      record.append(row) 
    print count 
    return record[0:4] 

在這裏，我能夠在0-4的範圍內讀取行。 但是有沒有可能使這個自動化，也就是說，我們可以不需要手動給出這個範圍，而是每次讀取下一行4行，直到CSV文件結束爲止。

CSV文件包含：

apple beer rice chicken 
apple beer rice  
apple beer   
apple mango  
milk beer rice chicken 
milk beer rice  
milk beer   
milk mango  

Answer 1

您可以使用yield：

def dataFromFile(fname): 
    record = [] 
    print'Opening the file is executed once' 
    count = 0 
    with open(fname) as f: 
     for row in csv.reader(f, delimiter=' '): 
      count += 1 
      fields = [field for field in row if field] 
      if fields: 
       record.append(fields) 
      if len(record) == 4: 
       print 'Last yielded row:', count 
       yield(record) 
       record = [] 
    if record: 
     yield record 

而且呼叫：

for row in dataFromFile('your.csv'): 
    print row 

從解釋

>>> import csv 
>>> 
>>> def dataFromFile(fname): 
    record = [] 
    print 'Opening the file is executed once' 
    count = 0 
    with open(fname) as f: 
     for row in csv.reader(f, delimiter=' '): 
      count += 1 

      fields = [field for field in row if field] 
      if fields: 
       record.append(fields) 
      if len(record) == 4: 
       print 'Last yielded row:', count 
       yield(record) 
       record = [] 
    if record: 
     yield record 
... 
>>> for row in dataFromFile('your.csv'): 
...  print row 
... 
Opening the file is executed once 
Last yielded row: 4 
[['apple', 'beer', 'rice', 'chicken'], ['apple', 'beer', 'rice'], ['apple', 'beer'], ['apple', 'mango']] 
Last yielded row: 8 
[['milk', 'beer', 'rice', 'chicken'], ['milk', 'beer', 'rice'], ['milk', 'beer'], ['milk', 'mango']] 
>>>