Tags down


Get memory address of an R data frame

By : FinleyMa
Date : September 15 2020, 05:00 AM
Does that help Rcpp passes by reference. I.e. it passes pointers to R objects, not their values. So you can manipulate them in C++ in the same way as any pointer.
code :

void f1(DataFrame x) {
  IntegerVector V1 = x["V1"];
  V1 = V1 * 2;

x = data.frame(V1 = 1:5, V2 = 1:5)
#   V1 V2
# 1  2  1
# 2  4  2
# 3  6  3
# 4  8  4
# 5 10  5

Share : facebook icon twitter icon

If a frame is 4KB then a system with 4 byte entries can address 2^36 bytes of physical memory. How is it 2^36?

By : user1285874
Date : March 29 2020, 07:55 AM
I wish this help you It looks like you are bit wrong with the quote. The book says: "A 32-bit entry can point to one of 2^32 physical page frames. If frame size is 4 KB (2^12), then a system with 4-byte entries can address 2^44 bytes (or 16 TB) of physical memory"
in such representation - the 2^44 is logical. We have 2^32 frames, where each frame, on x32 system, can hold 2^12 entries (4 KB frame size. The entry is 4 bytes - pointer size on x32 systems). So having that: 2^32 * 2^14 = 2^44 - total amount of bytes that frames can hold.

How to generate data frame variable name on the fly and address existing data frame variable with it?

By : clement
Date : March 29 2020, 07:55 AM
I hope this helps you . Short answer: use [[ instead of $, e.g. df[[paste0("v",a)]].
get() is not generally recommended, but if you need to use it, you'll have to do this in two steps:
code :

how to copy PyObject * memory data to another memory address?

By : darshana chauhan
Date : March 29 2020, 07:55 AM
With these it helps The easiest way would be to pickle your Python object into a string and copy the string into the shared memory. Then, the other process would unpickle it back into a Python object. From manual:

In a call stack that grows from high to low address, are the data elements saved from low memory address to high memory

By : Johey
Date : March 29 2020, 07:55 AM
I wish this help you Endianness is completely irrelevant, why is that even being mentioned.
Why didnt you just try it and find out? Of course it is compiler/calling convention specific, but using the compiler you care about easy to figure out.

How can I divide sub-selections of a data frame by another data frame using minimal memory usage in python?

By : Mai Abo-Elmaaty
Date : March 29 2020, 07:55 AM
To fix the issue you can do I have a dataframe with many columns and I want to divide it by another data frame at regular column intervals with minimal memory usage. , Using pd.concat:
code :
res = pd.concat([df2]*5, 1)
res.columns = df1.columns

          0         1         2         3    ...            6         7         8         9
0  1.000000  0.666667  3.000000  1.333333    ...     7.000000  2.666667  9.000000  3.333333
1  1.428571  1.500000  1.142857  1.166667    ...     0.571429  0.500000  0.285714  0.166667
2  0.222222  1.333333  0.333333  0.333333    ...     0.777778  2.666667  1.000000  1.333333
res = pd.concat([df2]*(df1.shape[1]//df2.shape[1]), 1)
Related Posts Related Posts :
  • C++ template function resolution in splitted namespaces
  • I am trying to swap two values by pass by reference there is no error occur but the compiler throw some message
  • How could I obtain the common keys of two std::map?
  • Default argument in struct c++
  • How to make a variable cycle through range?
  • C++ sum of vector values (recursive)
  • How do I proceed with a question like this?
  • If the A class's member function is changed, client binary of the A class need to be rebuild?
  • Capture arguments are copied from rvalue lambda?
  • C++ program not running on windows systems without VS installed "VCRUNTIME140.dll was not found"
  • Know if template parameter is const char* at compile time?
  • Return value changes partially and deterministically
  • How to use typedef to create multiple arrays?
  • How to get to the Nth node in the Linked list?
  • Warning: "variable may be used uninitialized in this function" in a multi-mode structured function
  • I am trying to print some corresponding values to a character but condition always going to else
  • Can I generate 64-Bit application binary from a 32-Bit GCC compiler?
  • Restinction on values for operator+ overload in templated class
  • C++: array of vectors
  • Hackerrank: Day 1: Data Types in C++
  • How to insert elements into shared pointer of std::map?
  • Is an initializer list static enough to allow instantiating templates?
  • Minimize button won't appear on MFC Dialog
  • Why does const prevent this from compiling?
  • Averaging ADC readings have strange steps in plot
  • Rock,Paper, Scissors Program Game
  • Why pow(10,2)=99 & pow(10,3)=1000?
  • What is the lifetime of C++ member variables when running in a std::thread?
  • C++ | Print tree (not necessarily binary) in a pretty way to stdout
  • The difference between delete and the destructor when both called?
  • What happens inside of a C++ constructor?
  • Mixing overriding and overloading in C++
  • Is std::stringstream::flush() supposed to do anything?
  • How does Qt::DirectConnection act when used in multi-threaded environment?
  • bison/flex: calculator interprets double values as integers so I added #define YYSTYPE double, but I multiple compilatio
  • Register the environment varibles for TBB
  • modelo of square is zero, factorial modelo problem
  • Split student list that has format like: 0001 William Bill Junior 8.5
  • How to use the overloaded "operator<<" properly?
  • Why Smart pointers can not be declared the usual Pointer way
  • I can't figure out what is wrong my implementation of MST with Kruskal algorithm
  • C++ how would one simplify this template so that it is not specialized?
  • What happens when a reference of an object (with different types) is deleted?
  • Is main() always on the stack?
  • What if one process in a MPI program proceeds more slowly than others?
  • I'm trying to get current date and time in cpp but can't understand these lines
  • make_pair() in C++
  • How can I access to derived members from a pure virtual base class function?
  • Constructor cannot be redeclared. Why?
  • Is there any similar function to glibc mtrace() function in c++?
  • faster erase-remove idiom when I don't care about order and don't have duplicates?
  • How to store variable as nothing
  • How to properly free a set of pointers?
  • C++ file IO - ASCII value instead of Binary value
  • Weird behavior of a simple for-loop code using "find" function in C++(to increment value if a certain sub-stri
  • I want two loops to run in parallel
  • Why would it be good to use dynamic memory allocation with serial communication?
  • non static member in static cpp
  • Non type template parameter
  • 3x3 Matrix Rotation with non uniform scaling
  • shadow
    Privacy Policy - Terms - Contact Us © 35dp-dentalpractice.co.uk