[英]How do I create new columns based off of a list derived from an existing column in python/pandas?
[英]How do I create a new column based on existing columns in pandas?
尝试:
x['b'] = np.log(x['a']/x['a'].shift())
Output:
a b
0 2340 NaN
1 2304 -0.015504
2 2238 -0.029064
3 2260 0.009782
4 2315 0.024045
5 2318 0.001295
6 2300 -0.007796
7 2310 0.004338
8 2353 0.018444
9 2350 -0.001276
您可以将生成器 function 与.apply
一起使用:
import numpy as np
import pandas as pd
x = pd.DataFrame(
[2340, 2304, 2238, 2260, 2315, 2318, 2300, 2310, 2353, 2350], columns=["a"]
)
def fn():
old_a = np.nan
a = yield
while True:
new_a = yield np.log(a / old_a)
a, old_a = new_a, a
s = fn()
next(s)
x["b"] = x["a"].apply(lambda v: s.send(v))
print(x)
印刷:
a b
0 2340 NaN
1 2304 -0.015504
2 2238 -0.029064
3 2260 0.009782
4 2315 0.024045
5 2318 0.001295
6 2300 -0.007796
7 2310 0.004338
8 2353 0.018444
9 2350 -0.001276
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