从字典 Python 内的列表中删除元素

Question

Hello i have a dict like this one :

{
   "a":{
      "a1":val,
      "a2":val
   },
   "b":{
      "b1":[
          {
             "measure":{
                 "k":"v",
                 "k1":"v"
             },
             "ts":"2020-10-12T12:12:12"
          },
          {
             "measure":{
                 "k":"v",
                 "k1":"v"
             },
             "ts":"2020-10-12T12:12:12"
          },
      ]
   }
}

I need to remove some dicts from the list of dicts dict["b"]["b1"]

so i imagined my code like this :

def epc_avionics_treatment(self,dict_data):
    i=0
    for epc1 in dict_data["b"]["b1"]:
        if (epc1["ts"]=="200-00-00T00:00:00Z"):
            del dict_data["b"]["b1"][i]
        i=i+1
    
        
    if (len(dict_data["b"]["b1"])==0):
        del dict_data["b"]["b1"]
    return dict_data

However elements from the list are not removed even if "ts" key equals to my criteria of removal i also tried to assign dict["b"]["b1"] to vars but it has no impact.

Answer 1

It is happening because when you are deleting the element you dont need to increment your index var.
Working example:

def epc_avionics_treatment(dict_data):
    i=0
    while i<len(dict_data["b"]["b1"]):
        if (dict_data["b"]["b1"][i]["ts"]=="200-00-00T00:00:00Z"):
            del dict_data["b"]["b1"][i]
            i-=1
        i=i+1
    
        
    if (len(dict_data["b"]["b1"])==0):
        del dict_data["b"]["b1"]
    return dict_data

Answer 2

Your code is experiencing a logical error. When you delete a node by following commands

del dict_data["b"]["b1"][i]

and then increasing the i, you are going wrong because you are skipping one another node. I'm going to explain it in the below :

items = [a1,a2,a3,a4,a5]

i=3 // So items[2] : a3

// lets delete items[i]

del items[i] // a3 has been removed.

// now , items[i] is a4 ( i have not increased i yet ), so what happen if i increase the i ? 
i = i + 1 // now items[i] is a5 and i have skipped a4

//if i delete items[i], a5 would be removed and not a4