Python-从List元素初始化List变量

Question

Ex. Lets consider, I have a list,

list_var = ['sales_qty' , 'returns_qty' , 'net_sales_qty' , 'sales_amt' , 'returns_amt' ,'product_discount_amt' , 'product_net_amt' ,'product_cost_amt' , 'gross_sales_amt' , 'supplier_disc_amt' , 'category_disc_amt' , 'topup_disc_amt' , 'value_at_cost']

from this list element, i want to init these elements as list in the memory, so i could use append, extend method for these elements.

As follow,

#Need these variable in memory..
sales_qty = [], returns_qty  = [], net_sales_qty = [] ... value_at_cost = []

#list operation on variable..
sales_qty.append(5)

Is there any simple way to do that, so i could remove element or add element in list easily?

Answer 1

You could create a dictionary of lists based on list_var .

list_var = ['sales_qty' , 'returns_qty' , 'net_sales_qty' , 'sales_amt' , 'returns_amt' ,'product_discount_amt' , 'product_net_amt' ,'product_cost_amt' , 'gross_sales_amt' , 'supplier_disc_amt' , 'category_disc_amt' , 'topup_disc_amt' , 'value_at_cost']

list_dic = {k: [] for k in list_var}

Now can access your lists through the list_dic dict:

list_dic['sales_qty'].append(123)
list_dic['category_disc_amt'].append('abc')

---

If you're using a python version that does not support dict comprehensions (python 2.6 or lower), you can use a list comprehension instead (as DSM explained in his comment):

list_dic = dict((k, []) for k in list_var)

Answer 2

Use vars if you are invoking from global scope. Otherwise, use globals .

list_var = ['sales_qty' , 'returns_qty' , 'net_sales_qty' , 'sales_amt' , 'returns_amt' ,'product_discount_amt' , 'product_net_amt' ,'product_cost_amt' , 'gross_sales_amt' , 'supplier_disc_amt' , 'category_disc_amt' , 'topup_disc_amt' , 'value_at_cost']

for item in list_var:
    vars()[item] = []

sales_qty.append(1)
sales_qty.append(3)
returns_qty.append(2)

print "Outside..."
print sales_qty
print returns_qty


def foo():
    global sales_qty

    sales_qty.append(4)

    print "Inside foo..."
    print sales_qty
    print returns_qty

    # This works if you want the whole thing inside a function
    print "Variable from inside foo..."
    globals()["new_var"] = []
    new_var.append(5)
    print new_var

foo()

print "Outside again..."
print sales_qty
print returns_qty

Output:

>>> 
Outside...
[1, 3]
[2]
Inside foo...
[1, 3, 4]
[2]
Variable from inside foo...
[5]
Outside again...
[1, 3, 4]
[2]
>>> 

Answer 3

You mean something like this:

list_var = [ 'abc', 'cde', 'fgh' ]

dict_var = dict()
for x in list_var:
    dict_var[x] = []

dict_var['abc'].append(5)