Pandas 使用 for 循环创建多个数据框

Question

I am looking for efficient Python codes to:

1. Create multiple data frames 2. Loop over the multiple data frames

For instance, in my code:

os.chdir(EU_path)
csv_files = glob.glob(EU_path + '\*.csv')
list_EU_data = []
for filename in csv_files:
    data = pd.read_csv(filename)
    list_EU_data.append(data)

list_EU_data is a list of 10 csv files of product sales from 10 European countries. For instance, list_EU_data[0] returns a data frame with columns related to sales information.

Here, I want to create multiple data frames while pre-processing data frames, for instance,

First select columns

EU[0] = list_EU_data[0].iloc[:, [0, 1]]
EU[1] = list_EU_data[1].iloc[:, [0, 1]]
...continues...
EU[9] = list_EU_data[9].iloc[:, [0, 1]]

Next, from each of the data frames, I want to replace 0 values by 1 and iterate all the data frames:

EU[0].iloc[:, 1] = EU[0].iloc[:, 1].replace(0, 1)
EU[1].iloc[:, 1] = EU[1].iloc[:, 1].replace(0, 1)
...continues...
EU[9].iloc[:, 1] = EU[9].iloc[:, 1].replace(0, 1)

Using for loop, what's the most efficient ways to write the above code?

Answer 1

If need loop solution working with list of DataFrame s:

for i, df1 in enumerate(EU):
    df1 = df1.iloc[:, [0, 1]]
    df1.iloc[:, 1] = df1.iloc[:, 1].replace(0, 1)
    EU[i] = df1

Also is possible change your code:

os.chdir(EU_path)
csv_files = glob.glob(EU_path + '\*.csv')
list_EU_data = []
for filename in csv_files:
    data = pd.read_csv(filename)
    data = data.iloc[:, [0, 1]]
    data.iloc[:, 1] = data.iloc[:, 1].replace(0, 1)
    list_EU_data.append(data)

Answer 2

请参考我的评论： https : //stackoverflow.com/a/64798278/9967586用于创建多个数据框并循环遍历这些 dfs