python从txt文件中读取数字，并放入list中

Question

a.txt文件内容是：
34,23,4.5
44,5.6,65
2,33,34
需要读取这个文件中的所有数据并放到一个list中。结果应该是
result=[[34, 23, 4.5],
[44, 5.6, 65],
[2, 33, 34]]
请教怎么能得到这个result呢？
谢谢哈！
我写的程序是：
result=[]
f=file('a.txt','r')
for line in f.readlines():
# data=f.readline()
result.append(line.split(','))
f.close
运行后的结果是
['3', '4', '50\n']
['4', '5', '68\n']
['6', '7', '49\n']
['3', '4', '57']
不是类型不对还好，后面的\n怎么删掉啊

Answer 1

python3.x

result=[]
with open('a.txt','r') as f:
for line in f:
result.append(list(map(float,line.split(','))))
print(result)

python2.7
result=[]
with open('a.txt','r') as f:
for line in f:
result.append(map(float,line.split(',')))
print(result)

Answer 2

result.append(line.split(',')[:-1])

Answer 3

for line in f:

line = line.replace('\n', '')
result.append(line.split(","))