[英]python for loop with if statement to divide numbers
if statement and for loop if 语句和 for 循环
I am stuck with the following code, I have a column in which I want to divide by 2 if the number is above 10 and run this for all the rows.我坚持使用以下代码,如果数字大于 10,我想在其中除以 2 并为所有行运行此列。 I have tried this code but it gives the error of the series is ambiguous:
我已经尝试过这段代码,但它给出了该系列的错误是模棱两可的:
if df[x] > 10:
df[x]/2
else:
df[x]
I suppose that I need a for loop in combination with the if statement.我想我需要一个结合 if 语句的 for 循环。 However I could not make it running, anyone has some ideas?
但是我无法让它运行,有人有什么想法吗?
It's not clear exactly what you're asking, but assuming you want to divide the element at x if it is > 10, you can simply do目前尚不清楚你在问什么,但假设你想在 x 处划分元素,如果它> 10,你可以简单地做
>>> df = [1,2,3,4,5,6]
>>> df = [1,2,30,40,5,6]
>>> if df[2]>10:
... df[2]/=2
...
>>> df
[1, 2, 15.0, 40, 5, 6]
Note the /= instead of your /.注意 /= 而不是 /。
The easiest approach, I think, is to use boolean indexing.我认为最简单的方法是使用布尔索引。 For example:
例如:
df = pd.DataFrame( # create dataframe
20*np.random.rand(6, 4),
columns=list("ABCD"))
print(df) # print df
df[df>10]/=2 # divide entries over 10 by 2
print(df) # print df
Result:结果:
A B C D
0 1.245686 1.443671 17.423559 17.617235
1 13.834285 10.482565 2.213459 9.581361
2 0.290626 14.082919 0.224327 11.033058
3 5.113568 5.305690 19.453723 3.260354
4 14.679005 8.761523 2.417432 4.843426
5 15.990754 12.421538 4.872804 5.577625
A B C D
0 1.245686 1.443671 8.711780 8.808617
1 6.917143 5.241283 2.213459 9.581361
2 0.290626 7.041459 0.224327 5.516529
3 5.113568 5.305690 9.726862 3.260354
4 7.339503 8.761523 2.417432 4.843426
5 7.995377 6.210769 4.872804 5.577625
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