Problems while reformating a list of tuples, by taking only the first value of the tuple?

Question

I have the following list of tuples:

>>>lis = df['vals'].values.tolist()
>>>lis
[[('apple', 'FRUIT'),
          ('$', 'SYM'),
          ('6.00', 'X'),
          ('bannana', 'FRUIT'),
          ('$', 'SYM'),
          ('4.00', 'X')]]

How can I reformat it into:

lis = [['apple: $ 6.00', 'bannana: $ 4.00']]

I tried to:

list_comp = [item for sublist in lis for item in sublist]
list_comp = [' '.join(item) for t in list_comp for item in [t]]

However I do not get how to put the : and the above format.

Answer 1

您可以使用理解并将": $ "与元组元素连接起来：

print [lis[0][i][0] + ": $ " + lis[0][i+2][0] for i in range(0,len(lis[0]),3)]

Answer 2

First, define a function:

>>> def format_tuple(fruit, sym, x):
...   return "{}: {} {}".format(fruit, sym, x)
... 

Then,

>>> my_list
[[('apple', 'FRUIT'), ('$', 'SYM'), ('6.00', 'X'), ('bannana', 'FRUIT'), ('$', 'SYM'), ('4.00', 'X')]]
>>> my_list = my_list[0]
>>> by_three = (my_list[i:i + 3] for i in range(0,len(my_list), 3))
>>> [format_tuple(*(c[0] for c in chunk)) for chunk in by_three]
['apple: $ 6.00', 'bannana: $ 4.00']

And, I suppose if you really want it wrapped in a list, that last line could be:

>>> [[format_tuple(*(c[0] for c in chunk)) for chunk in by_three]]
[['apple: $ 6.00', 'bannana: $ 4.00']]