I have a csv file I am putting into a empty list, line by line, so the end result is a nested list with each line in a list e.g:

```
[[1.1,2.6,3,0,4.8],[3.5,7.0,8.0]....and so on.....].

```

The problem is at the end of the file are empty strings which end up in the final list like:

```
[[1.1,2.6,3,0,4.8],[3.5,7.0,8.0],['','','','','','','','','']]

```

How do I get rid of these or stop them being appended to the list. They are quite big csv files so I would prefer to stop them being appended to intial list. I feel I am building a extra large list when I probably don't need too, and this may cause memory issues.
Here is code so far:

```
csvfile = open(file_path, 'r')
reader = csv.reader(csvfile)
data_list = []

for row in reader:
    data_list.append(row)
csvfile.close()
i = 0
file_data = []

while i < len(data_list):
    j = 0
    while j < len(data_list[i]):
        try:
            data_list[i][j] = float(data_list[i][j])
        except ValueError:
            pass            
        j += 1
    file_data.append(data_list[i])
    i += 1

print file_data

```