Creating aggregated tables with calculations using loops in R

Question

Wondering how I can create a table with the results of different calculations in R. Here's an example using mtcars df

# Load tidyverse
library(tidyverse)

# Select only cyl vs and am from mtcars for simplicity
mt_select <- select(mtcars, c(cyl, vs, am))


# Here is the table I wish to make using some type of looping function
# (I have like 40 variables in actual dataset)
freq_table <- mt1 %>% group_by(cyl) %>% 
  summarise(n = n(),
            vs_sum = sum(vs),
            vs_perc = sum(vs)/n*100,
            am_sum = sum(am),
            am_perc = sum(am)/n*100)
print(freq_table)

Here is my attempt. Main issues I can't figure out:

1. Includes sums for "0" answers,
2. I don't know how to add a percent column
3. Don't know how to merge these all into one table

# make a vector to loop through
mt_vars <- names(mt_select)

# Loop to make tables
for (i in mt_vars){
  mt_select %>% 
    group_by(cyl) %>% 
    count_(i) %>%
    print()
}

Been trying to figure out how to make this for months and always just decide I don't need the table, or something else. Any help is greatly appreciated!!

Answer 1

connect has implicit Qt::ConnectionType parameter. It will be defined as Qt::QueuedConnection when sender and receiver are in different threads. You can use QObject::moveToThread to move worker to another thread.
If for some reason you want use QtConcurrent::run here - you can use it inside func1 implementation.
Check both versions:

class Worker : public QObject {
 public:
  void DoSlowCalculation() {
    qDebug() << "Worker::DoSlowCalculation thread:" << QThread::currentThreadId();
    QThread::msleep(2000);  // 2 sec
    qDebug() << "Worker::DoSlowCalculation finished";
  }
};

class ConcurrentExecutor : public QObject {
 public:
  void DoSlowCalculation() {
    qDebug() << "ConcurrentExecutor::DoSlowCalculation thread:" << QThread::currentThreadId();
    QThread::msleep(2000);  // 2 sec
    qDebug() << "ConcurrentExecutor::DoSlowCalculation finished";
  }
  void DoSlowCalculationConcurrent() {
    QtConcurrent::run(this, &ConcurrentExecutor::DoSlowCalculation);
  }
};

int main(int argc, char** argv) {
  QApplication app(argc, argv);
  
  qDebug() << "Main thread:" << QThread::currentThreadId();
  
  QThread worker_thread;
  Worker worker;
  worker.moveToThread(&worker_thread);
  worker_thread.start();

  QPushButton btn;
  btn.setText("Click to perform slow calculation");

  QObject::connect(&btn, &QAbstractButton::clicked, &worker,
                   &Worker::DoSlowCalculation);

  ConcurrentExecutor concurr_executor;
  QObject::connect(&btn, &QAbstractButton::clicked, &concurr_executor,
                   &ConcurrentExecutor::DoSlowCalculationConcurrent);

  worker_thread.start();

  QObject::connect(&app, &QCoreApplication::aboutToQuit, &worker_thread,
                   &QThread::quit);
  btn.show();
  return app.exec();
}

P.S. Strongly suggest to stop using SIGNAL and SLOT macros, that's Qt4 way to connect. More info on this topic here.