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Summarizing multiple columns with dplyr? [duplicate]
I'm struggling a bit with the dplyr-syntax. I have a data frame with different variables and one grouping variable. Now I want to calculate the mean for each column within each group, using dplyr in R.
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How to convert list of key-value tuples into dictionary?
I have a list that looks like:
7 Answers
7
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What's the meaning of interface{}?
I'm new to interfaces and trying to do SOAP request by github
6 Answers
6
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What is the proper way to check for null values?
I love the null-coalescing operator because it makes it easy to assign a default value for nullable types.
10 Answers
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When do you use varargs in Java?
I'm afraid of varargs. I don't know what to use them for.
8 Answers
8
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C语言结构体里的成员数组和指针 - c++1y / stl - 清泛IT社区，为创新赋能！
...把代码copy过去编译和调试，我把代码列在下面：#include <stdio.h>
struct str{
int len;
char s[0];
};
struct foo {
struct str *a;
};
int main(int argc, char** argv) {
struct foo f={0};
if (f.a->s) {
&n...
printf format specifiers for uint32_t and size_t
I have the following
4 Answers
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Testing if object is of generic type in C#
I would like to perform a test if an object is of a generic type. I've tried the following without success:
5 Answers
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The difference between the Runnable and Callable interfaces in Java
What is the difference between using the Runnable and Callable interfaces when designing a concurrent thread in Java, why would you choose one over the other?
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Method call if not null in C#
Is it possible to somehow shorten this statement?
11 Answers
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