使用pyspark循环连接字符串

Question

我是pyspark的新手，下面有一个文本文件：

XXX,
YYY,123.67789

,

X1X1X1,

Y1Y1Y1,123.64447789

Y2Y2Y2,123.64447789
,

X3X3X3,

Y4Y4Y4,123.64447789

Y5Y5Y5,123.64447789

Y6Y6Y6,143.64447789

使用pyspark（映射功能或for循环）将其转换为csv文件，如下所示：

XXX,YYY,123.67789

X1X1X1,Y1Y1Y1,123.64447789

X1X1X1,Y2Y2Y2,123.64447789

X3X3X3,Y4Y4Y4,123.64447789

X3X3X3,Y5Y5Y5,123.64447789

X3X3X3,Y6Y6Y6,143.64447789

已尝试for循环，但未按预期工作

for line i list:
   if(line[-1: == ","])
      result1 = line 
   else:
      result = result1 + result + line