Joseph Toth created ARROW-2787:
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Summary: Memory Issue passing table from python to c++ via cython
Key: ARROW-2787
URL: https://issues.apache.org/jira/browse/ARROW-2787
Project: Apache Arrow
Issue Type: Bug
Components: Integration
Affects Versions: 0.9.0
Environment: clang6
Reporter: Joseph Toth
I wanted to create a simple example of reading a table in Python and pass it to
C++, but I'm doing something wrong or there is a memory issue. When the table
gets to C++ and I print out column names it also prints out a lot of junk and
what looks like pydocs. Let me know if you need any more info. Thanks!
*demo.py*
??import numpy??
??from psy.automl import cyth??
??import pandas as pd??
??from absl import app??
??def main(argv):??
?? sup = pd.DataFrame({??
?? 'int': [1, 2],??
?? 'str': ['a', 'b']??
?? })??
?? table = pa.Table.from_pandas(sup)??
?? cyth.c_t(table)??
*??cyth.pyx??*
??import pandas as pd??
??import pyarrow as pa??
??from pyarrow.lib cimport *??
??cdef extern from "cyth.h" namespace "psy":??
??void t(shared_ptr[CTable])??
??def c_t(obj):??
# ??These print work??
??# for i in range(obj.num_columns):??
??# print(obj.column(i).name??
?? cdef shared_ptr[CTable] tbl = pyarrow_unwrap_table(obj)??
?? t(tbl)??
*cyth.h*
??#include <iostream>??
??#include <string>??
??#include "arrow/api.h"??
??#include "arrow/python/api.h"??
??#include "Python.h"??
??namespace psy {??
??void t(std::shared_ptr<arrow::Table> pytable) {??
??// This works??
?? std::cout << "NUM" << pytable->num_columns();??
??// This prints a lot of garbage??
?? for(int i = 0; i < pytable->num_columns(); i++) {??
?? std::cout << pytable->column(i)->name();??
?? }??
??}??
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