优化 Python 代码以加快处理速度

Question

I need some help/suggestions/guidance on how I can optimize my code. The code works, but with huge data it has been running for almost a day. My data has ~ 2 million rows, with sample data ( few thousdand rows) it works.My sample data format is show below:

index   A    B
0   0.163   0.181
1   0.895   0.093
2   0.947   0.545
3   0.435   0.307
4   0.021   0.152
5   0.486   0.977
6   0.291   0.244
7   0.128   0.946
8   0.366   0.521
9   0.385   0.137
10  0.950   0.164
11  0.073   0.541
12  0.917   0.711
13  0.504   0.754
14  0.623   0.235
15  0.845   0.150
16  0.847   0.336
17  0.009   0.940
18  0.328   0.302

What I want to do : Given the above data set I want to bucket/bin each row into different buckets/bins based on values of A and B.Each index can only lie in one bin. To do this I have discretized A and B from 0 to 1( step size of 0.1). My bins for A look like this:

listA = [0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0] 

similar for B.

listB = [0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0]

So total I have 10 * 10 = 100 bin So in total there are 100 bins, bin1 = (A,B) = (0,0), bin 2 = (0,0.1), bin 3 = (0,0.2)....bin 10 = (0,1), bin 11 = (0.1,0).....bin 20 = (0.1,1)..... bin(100) = (1,1) Then for each index, I am checking which bin each index lies in running a for loop shown below:

for index in df.index:
  sumlist = []
  for A in listA:
    for B in listB:
      filt_data = df[(df['A'] > A) & (df['A'] < A) & (df['B'] > B) & (df_input['B'] < B)]
      data_len = len(filt_data)
      sumlist = sumlist.append(data_len)
      df_sumlist = pd.DataFrame([sumlist])
   df_output = pd.concat([df_output , df_sumlist ] , axis = 0)

I tried using the pandas cut function for binning but it appears that it works for one column.

Expected output

index   A         B    bin1   bin2 bin3 bin4 bin5 ...bin 23.. bin100    
    0   0.163   0.181   0      0     0   0    0           1     0
    1   0.895   0.093
    2   0.947   0.545
    3   0.435   0.307
    4   0.021   0.152
    5   0.486   0.977
    6   0.291   0.244
    7   0.128   0.946
    8   0.366   0.521
    9   0.385   0.137
    10  0.950   0.164
    11  0.073   0.541
    12  0.917   0.711
    13  0.504   0.754
    14  0.623   0.235
    15  0.845   0.150
    16  0.847   0.336
    17  0.009   0.940
    18  0.328   0.302

I do care about other bins even if they are zero, for eg: index 0 might lie in bin 23 so for index 0 I will have 1 in bin 23 and 0 in all other 99 bins. Similarly for index 1, it might lie in bin 91, so expected to have 1 in bin 91 and all bins 0 for index.

Thanks for taking the time to read and help me with this, appreciate your help. Please let me know if I am missing anything or need to clarify things.

Answer 1

You were on the right track! pd.cut is the way to go. I'm using the Series categories to create your final bins:

import pandas as pd
import numpy as np

# Generate sample df
df = pd.DataFrame({'A': np.random.uniform(size=20), 'B': np.random.uniform(size=20)})

# Create bins for each column
df["bin_A"] = pd.cut(df["A"], bins=np.linspace(0, 1, 11))
df["bin_B"] = pd.cut(df["B"], bins=np.linspace(0, 1, 11))

# Create a combined bin using category codes for each binned column
df["combined_bin"] = df["bin_A"].cat.codes * 10 + df["bin_B"].cat.codes
df["combined_bin"] = pd.Categorical(df["combined_bin"], categories=range(100))

# Loop over categories to create new columns
for i in df["combined_bin"].cat.categories:
    df[f"bin_{i}"] = (df["combined_bin"] == i).astype(int)

Answer 2

You could probably use cut on each column and then combine the results to find the category of the row

acat = pd.cut(df['A'], [.1*i for i in range(11)],
       labels = range(10), include_lowest=True)
bcat = pd.cut(df['B'], [.1*i for i in range(11)],
       labels = range(10), include_lowest=True)
cat = 1 + bcat.cat.codes + acat.cat.codes * 10

With your sample data, I get

0     12
1     81
2     96
3     44
4      2
5     50
6     23
7     20
8     36
9     32
10    92
11     6
12    98
13    58
14    63
15    82
16    84
17    10
18    34
dtype: int8

get_dummies and reindex will give the wide columns

w = pd.get_dummies(cat).reindex(columns=list(range(1,101))).fillna(0).astype('int8')

We only have to concat it to the original dataframe:

pd.concat([df, w], axis=1)

to get as expected:

        index      A      B  1  2  3  4  5  6  ...  92  93  94  95  96  97  98  99  100
0       0  0.163  0.181  0  0  0  0  0  0  ...   0   0   0   0   0   0   0   0    0
1       1  0.895  0.093  0  0  0  0  0  0  ...   0   0   0   0   0   0   0   0    0
2       2  0.947  0.545  0  0  0  0  0  0  ...   0   0   0   0   1   0   0   0    0
3       3  0.435  0.307  0  0  0  0  0  0  ...   0   0   0   0   0   0   0   0    0
4       4  0.021  0.152  0  1  0  0  0  0  ...   0   0   0   0   0   0   0   0    0
5       5  0.486  0.977  0  0  0  0  0  0  ...   0   0   0   0   0   0   0   0    0
6       6  0.291  0.244  0  0  0  0  0  0  ...   0   0   0   0   0   0   0   0    0
7       7  0.128  0.946  0  0  0  0  0  0  ...   0   0   0   0   0   0   0   0    0
8       8  0.366  0.521  0  0  0  0  0  0  ...   0   0   0   0   0   0   0   0    0
9       9  0.385  0.137  0  0  0  0  0  0  ...   0   0   0   0   0   0   0   0    0
10     10  0.950  0.164  0  0  0  0  0  0  ...   1   0   0   0   0   0   0   0    0
11     11  0.073  0.541  0  0  0  0  0  1  ...   0   0   0   0   0   0   0   0    0
12     12  0.917  0.711  0  0  0  0  0  0  ...   0   0   0   0   0   0   1   0    0
13     13  0.504  0.754  0  0  0  0  0  0  ...   0   0   0   0   0   0   0   0    0
14     14  0.623  0.235  0  0  0  0  0  0  ...   0   0   0   0   0   0   0   0    0
15     15  0.845  0.150  0  0  0  0  0  0  ...   0   0   0   0   0   0   0   0    0
16     16  0.847  0.336  0  0  0  0  0  0  ...   0   0   0   0   0   0   0   0    0
17     17  0.009  0.940  0  0  0  0  0  0  ...   0   0   0   0   0   0   0   0    0
18     18  0.328  0.302  0  0  0  0  0  0  ...   0   0   0   0   0   0   0   0    0