如何将数字重新编码为分类数据

Question

I am new to Python, I am studying it for data science purposes. Right now, I am trying to recode some numerical data (1,2,3 etc) into categories. It requires a little loop in the end, but I can't get that right. It causes a key error 3.

The dataset has 21 columns.

Can anyone help? Thanks!!

for col_dic in code_list:
col = col_dic[0]
dic = col_dic[1]
values[col] = [dic[x] for x in values[col]]

Answer 1

It is rather hard to understand what exactly you want to see in result, but the cause of this error is clear:

You are iterating through a list of lists. Every col_dic contains a col = col_dic[0] (string like 'property_type' ) and dic = col_dic[1] (dictionary). In the last line you are writing info to a values dict (I suppose you created it before). This error is appearing because dic doesn't contain a particular key from the values[col] . For example:

values[col] is equal to {1: [], 2: [], 3: []} and dic is equal to {1: 'One', 2: 'Two'} . When you are iterating through values[col] , you are trying to find a key 3 in dic . But it contains no 3 key, so the error is appearing. You should check that dic contains this key like this:

values_list = []
for v in values[col]:
    if v in dic:
        values_list.append(dic[v])
values[col] = values_list

Also note that your keys are strings represents integers. Your error can appear when you try to find a key '3' (string) in a dict contains keys like 3 (integers). So I suggest you to convert your keys to strings: str(key) .