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Can dplyr package be used for conditional mutating?
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220
Use ifelse
df %>%
mutate(g = ifelse(a == 2 | a == 5 | a == 7 | (a == 1 & b == 4), 2,
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Are members of a C++ struct initialized to 0 by default?
... constructors
struct Snapshot {
int x;
double y;
Snapshot():x(0),y(0) { }
// other ctors / functions...
};
Will initialize both x and y to 0. Note that you can use x(), y() to initialize them disregarding of their type: That's then value initialization, and usually yields a proper...
How do I check if there are duplicates in a flat list?
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406
Use set() to remove duplicates if all values are hashable:
>>> your_list = ['one', 't...
How to determine the longest increasing subsequence using dynamic programming?
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407
OK, I will describe first the simplest solution which is O(N^2), where N is the size of the col...
How do I trim leading/trailing whitespace in a standard way?
...m leading space
while(isspace((unsigned char)*str)) str++;
if(*str == 0) // All spaces?
return str;
// Trim trailing space
end = str + strlen(str) - 1;
while(end > str && isspace((unsigned char)*end)) end--;
// Write new null terminator character
end[1] = '\0';
re...
clearing a char array c
... to view this as a C/C++ null terminated string, setting the first byte to 0 will effectively clear the string.
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If vs. Switch Speed
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answered Jan 14 '09 at 23:16
Konrad RudolphKonrad Rudolph
461k118118 gold badges863863 silver badges11101110 bronze badges
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How to change navbar collapse threshold using Twitter bootstrap-responsive?
I'm using Twitter Bootstrap 2.0.1 in a Rails 3.1.2 project, implemented with bootstrap-sass. I'm loading both the bootstrap.css and the bootstrap-responsive.css files, as well as the bootstrap-collapse.js Javascript.
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Converting a column within pandas dataframe from int to string
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In [16]: df = DataFrame(np.arange(10).reshape(5,2),columns=list('AB'))
In [17]: df
Out[17]:
A B
0 0 1
1 2 3
2 4 5
3 6 7
4 8 9
In [18]: df.dtypes
Out[18]:
A int64
B int64
dtype: object
Convert a series
In [19]: df['A'].apply(str)
Ou...
What is the difference between quiet NaN and signaling NaN?
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70
When an operation results in a quiet NaN, there is no indication that anything is unusual until ...