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AppInventor2有没有删除撤销功能？ - App应用开发 - 清泛IT社区，为创新赋能！
问：不小心删除了组件，能撤回吗？
答：界面（组件）设计界面，没有撤销功能。代码（逻辑）设计视图，可以使用 Ctrl+Z 撤销，Ctrl+Y 反撤销。
界面设计没有撤销功能，有时不小心删除了组件，真的就没法恢复了，有时真...
Your build failed due to an error in the AAPT stage, not because of an...
大概率是因为项目名称是中文导致的，换成英文的就ok，这个问题先记录下来，后续fun23.cn平台可以解决。
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需要注意的事项：该项目已超过 30MB 的最大大小该项目已超出建议的最大 10 个...
How do I merge two dictionaries in a single expression in Python (taking union of dictionaries)?
I have two Python dictionaries, and I want to write a single expression that returns these two dictionaries, merged (i.e. taking the union). The update() method would be what I need, if it returned its result instead of modifying a dictionary in-place.
...
How to test multiple variables against a value?
...ying to make a function that will compare multiple variables to an integer and output a string of three letters. I was wondering if there was a way to translate this into Python. So say:
...
surface plots in matplotlib
...ing projection='3d' in add_subplot
import matplotlib.pyplot as plt
import random
def fun(x, y):
return x**2 + y
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
x = y = np.arange(-3.0, 3.0, 0.05)
X, Y = np.meshgrid(x, y)
zs = np.array(fun(np.ravel(X), np.ravel(Y)))
Z = zs.reshape(...
Pandas conditional creation of a series/dataframe column
...color'] = np.where(df['Set']=='Z', 'green', 'red')
For example,
import pandas as pd
import numpy as np
df = pd.DataFrame({'Type':list('ABBC'), 'Set':list('ZZXY')})
df['color'] = np.where(df['Set']=='Z', 'green', 'red')
print(df)
yields
Set Type color
0 Z A green
1 Z B green
2 ...
Preserving signatures of decorated functions
...rect signature on Python 3.4. Why do you think functools.wraps() is broken and not IPython?
– jfs
Jan 5 '16 at 4:35
1
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data.table vs dplyr: can one do something well the other can't or does poorly?
...able , not so much with dplyr . I've read through some dplyr vignettes and examples that have popped up on SO, and so far my conclusions are that:
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Call apply-like function on each row of dataframe with multiple arguments from each row
...mns. For each row in the dataframe, I want to call a function on the row, and the input of the function is using multiple columns from that row. For example, let's say I have this data and this testFunc which accepts two args:
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Is R's apply family more than syntactic sugar?
...regarding execution time and / or memory.
5 Answers
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