[英]Python pandas how to replace zeros in a column between values with these same values
I have a csv file in which such a column is calculated:我有一个 csv 文件,其中计算了这样的列:
Combined
0
0
1
0
0
0
2
0
0
0
3
0
0
0
0
-1
0
0
0
0
-2
0
0
0
0
-3
0
0
0
1
I would like to change the values in it so that when, for example, the value -1 appears, all zeros up to the value -2 turn into -1, which would turn out something like this我想更改其中的值,例如,当值 -1 出现时,值 -2 之前的所有零都变成 -1,结果是这样的
Combined
0
0
1
1
1
1
2
2
2
2
3
3
3
3
3
-1
-1
-1
-1
-1
-2
-2
-2
-2
-2
-3
-3
-3
-3
1
I combine it into class functions in this way像这样把class功能组合起来
cols = ['Answers', 'step', 'step2']
df['combined'] = df[cols].apply(lambda row: ''.join(row.values.astype(str)), axis=1)
df['combined'] = df['combined'].str.replace('0.000', 'O',regex=True)
df['combined'] = df['combined'].map(lambda x: x.lstrip('0.0').rstrip('.000'))
df['combined'] = df['combined'].str.replace('O', '0')
For the sake of explanation, At the beginning of this csv there is always a pair of zeros, but after them either -1 or 1 always comes and then it always goes depending on the first number either -2 or 2 and the three comes exactly the same depending on the second number either -3 or 3 And after its cycle repeats and also depending on the three.为了解释起见,在此 csv 的开头总是有一对零,但在它们之后总是出现 -1 或 1,然后它总是取决于第一个数字 -2 或 2,而三个正好出现相同取决于第二个数字 -3 或 3 并且在其循环重复之后也取决于三个。 either -1 or 1.
-1 或 1。
If need forward filling 0
to previous non 0
values use:如果需要将
0
向前填充到以前的非0
值,请使用:
df['Combined'] = df['Combined'].replace(0, np.nan).ffill().fillna(0).astype(int)
print (df)
Combined
0 0
1 0
2 1
3 1
4 1
5 1
6 2
7 2
8 2
9 2
10 3
11 3
12 3
13 3
14 3
15 -1
16 -1
17 -1
18 -1
19 -1
20 -2
21 -2
22 -2
23 -2
24 -2
25 -3
26 -3
27 -3
28 -3
29 1
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