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scala - Joining Spark dataframes on the key

I have constructed two dataframes. How can we join multiple Spark dataframes ? For Example : PersonDf, ... combining PersonDf and ProfileDf? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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cordova - How to use Google Analytics with Phonegap without a plugin?

I am making an app and I want to get analytics from the users. I tried to use the Phonegap Plugin, but I didn't ... than what I'm trying to do? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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How to store historical records in a history table in SQL Server

I have 2 tables, Table-A and Table-A-History. Table-A contains current data rows. Table-A-History ... different way to accomplish this? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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image processing - Automatic calculation of low and high thresholds for the Canny operation in opencv

In openCV, the low and high thresholds for the canny operator are mandatory: cvCanny(input,output,thresh1, ... calculation for opencv? thanks See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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user input - What does `scanf("%*[^ ]%*c")` mean?

I want to make a loop in C that, when the program asks for an integer and the user types a non-digit ... meanValue, grade); return 0; } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c# - Why does .NET foreach loop throw NullRefException when collection is null?

So I frequently run into this situation... where Do.Something(...) returns a null collection, like so: int ... would still be well defined. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - How can I convert a file pointer ( FILE* fp ) to a file descriptor (int fd)?

I have a FILE *, returned by a call to fopen(). I need to get a file descriptor from it, to make ... a file descriptor from a file pointer? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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Powershell equivalent of bash ampersand (&) for forking/running background processes

In bash the ampersand (&) can be used to run a command in the background and return interactive control to the ... usage in bash: sleep 30 & See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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javascript - Convert integer into its character equivalent, where 0 => a, 1 => b, etc

I want to convert an integer into its character equivalent based on the alphabet. For example: 0 => a 1 ... 's position in the alphabet. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Initializing a struct to 0

If I have a struct like this: typedef struct { unsigned char c1; unsigned char c2; } myStruct; What would be the ... ? myStruct _m2 = {0,0}; See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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php - Too much data with var_dump in symfony2 doctrine2

I have around 40 entities and many bidirectional relationships. Whenever i use var_dump($user) or any entity my ... cause issue in production. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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css position - CSS: Top vs Margin-top

I'm not sure if I fully understand the difference between these two. Can someone explain why I would use one over the other and how they differ? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c - Strings and character with printf

I was confused with usage of %c and %s in the following C program #include <stdio.h> void main() { char name[] ... argument 2 has type char *' See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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java - How can CopyOnWriteArrayList be thread-safe?

I've taken a look into OpenJDK source code of CopyOnWriteArrayList and it seems that all write operations ... is thread-safe? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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create anaconda python environment with all packages

I want to create an anaconda python environment with all of the packages that Continuum includes in its default ... to the cluster facility. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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Spark yarn cluster vs client - how to choose which one to use?

The spark docs have the following paragraph that describes the difference between yarn client and yarn cluster: ... suitable than the other. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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formarray - Angular Reactive Forms with nested Form Arrays

I'm new to Angular 2 and decided the best way to learn would be to go through the official Angular guides. I ... a Secret Lair</button> </div> See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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javascript - How to get Google Maps API to set the correct zoom level for a country?

Is there a was of automatically setting the zoom level based on the size of the country that the ... information freely available somewhere? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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Android RecyclerView : notifyDataSetChanged() IllegalStateException

I'm trying to update the items of a recycleview using notifyDataSetChanged(). This is my onBindViewHolder() ... adapter that something changed? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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unit testing - How to assert output with nosetest/unittest in python?

I'm writing tests for a function like next one: def foo(): print 'hello world!' So when I want to ... the output with unittest or nose module? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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python - Save multiple plots in a single PDF file

plotting module def plotGraph(X,Y): fignum = random.randint(0,sys.maxint) plt.figure(fignum) ### Plotting ... other way to accomplish it? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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Spring cannot find bean xml configuration file when it does exist

I am trying to make my first bean in Spring but got a problem with loading a context. I have a configuration ... the classpath. What's wrong? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to get the GL library/headers?

#include <glgl.h> #include <glglu.h> #include <glglaux.h> This is an example, but where to get GL headers? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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Using a Rails helper method within a javascript asset

Is there any way to use a Rails helper method, more specifically, a path helper method within a javascript asset file ... .val("path/to/create") See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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function - Using multiple .cpp files in c++ program?

I recently moved from Java for C++ but now when I am writing my application I'm not interested in writing ... my main function.. Any help? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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Using Java to pull data from a webpage?

I'm attempting to make my first program in Java. The goal is to write a program that browses to a ... about or recommend some good resources? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c# - What replaces WCF in .Net Core?

I am used to creating a .Net Framework console application and exposing a Add(int x, int y) function via a ... have to create a RESTful service? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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How to parse multiple nested sub-commands using python argparse?

I am implementing a command line program which has interface like this: cmd [GLOBAL_OPTIONS] {command [ ... line arguments useing argparse? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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