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How to select rows with one or more nulls from a pandas DataFrame without listing columns explicitly
...0, 0, np.NaN], range(3), range(3)])
>>> df.isnull()
0 1 2
0 False False False
1 False True False
2 False False True
3 False False False
4 False False False
>>> df.isnull().any(axis=1)
0 False
1 True
2 True
3 False
4 False
dtype: bo...
Do htmlspecialchars and mysql_real_escape_string keep my PHP code safe from injection?
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241
When it comes to database queries, always try and use prepared parameterised queries. The mysqli...
Counting the number of elements with the values of x in a vector
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18 Answers
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Pandas - How to flatten a hierarchical index in columns
I have a data frame with a hierarchical index in axis 1 (columns) (from a groupby.agg operation):
17 Answers
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Counting inversions in an array
I'm designing an algorithm to do the following: Given array A[1... n] , for every i < j , find all inversion pairs such that A[i] > A[j] . I'm using merge sort and copying array A to array B and then comparing the two arrays, but I'm having a difficult time seeing how I can use this to find...
Creating a Pandas DataFrame from a Numpy array: How do I specify the index column and column headers
...umns to DataFrame constructor, as in:
>>> pd.DataFrame(data=data[1:,1:], # values
... index=data[1:,0], # 1st column as index
... columns=data[0,1:]) # 1st row as the column names
edit: as in the @joris comment, you may need to change above to np.int_(dat...
Difference between Math.Floor() and Math.Truncate()
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12 Answers
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MySQL selecting yesterday's date
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168
The simplest and best way to get yesterday's date is:
subdate(current_date, 1)
Your query w...
How to remove leading and trailing whitespace in a MySQL field?
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11 Answers
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逆向工程——二进制炸弹(CSAPP Project) - 操作系统(内核) - 清泛网 - 专注...
...了一下，差不多几十页的样子，发现其中有六个函数phase_1……phase_6，基本上也就可以确定就是这六个关卡了。
===============phase_1===============
知识点：string，函数调用，栈
用了差不多一个星期断断续续地寻找感觉的phase_1，最...