Manually building a deep copy of a ConfigParser in Python 2.7 - python-2.7

Just starting in on my Python learning curve, and hitting a snag in porting some code up to Python 2.7. It appears that in Python 2.7 it is no longer possible to perform a deepcopy() on instances of ConfigParser. It also appears that the Python team isn't terribly interested in restoring such a capability:
http://bugs.python.org/issue16058
Can someone propose an elegant solution for manually constructing a deepcopy/duplicate of an instance of ConfigParser?
Many thanks, -Pete

This is just an example implementation of Jan Vlcinsky answer written in Python 3 (I don't have enough reputation to post this as a comment to Jans answer). Many thanks to Jan for the push in the right direction.
To make a full (deep) copy of base_config into new_config just do the following;
import io
import configparser
config_string = io.StringIO()
base_config.write(config_string)
# We must reset the buffer ready for reading.
config_string.seek(0)
new_config = configparser.ConfigParser()
new_config.read_file(config_string)

Based on #Toenex answer, modified for Python 2.7:
import StringIO
import ConfigParser
# Create a deep copy of the configuration object
config_string = StringIO.StringIO()
base_config.write(config_string)
# We must reset the buffer to make it ready for reading.
config_string.seek(0)
new_config = ConfigParser.ConfigParser()
new_config.readfp(config_string)

The previous solution doesn't work in all python3 use cases. Specifically if the original parser is using Extended Interpolation the copy may fail to work correctly. Fortunately, the easy solution is to use the pickle module:
def deep_copy(config:configparser.ConfigParser)->configparser.ConfigParser:
"""deep copy config"""
rep = pickle.dumps(config)
new_config = pickle.loads(rep)
return new_config

If you need new independent copy of ConfigParser, then one option is:
have original version of ConfigParser
serialize the config file into temporary file or StringIO buffer
use that tmpfile or StringIO buffer to create new ConfigParser.
And you have it done.

If you are using Python 3 (3.2+) you can use the Mapping Protocol Access to copy (actually deep copy) the sections and options of a source configuration to another ConfigParser object.
You can use read_dict() to copy the state of a configuration parser.
Here is a demo:
import configparser
# the configuration to deep copy:
src_cfg = configparser.ConfigParser()
src_cfg.add_section("Section A")
src_cfg["Section A"]["key1"] = "value1"
src_cfg["Section A"]["key2"] = "value2"
# the destination configuration
dst_cfg = configparser.ConfigParser()
dst_cfg.read_dict(src_cfg)
dst_cfg.add_section("Section B")
dst_cfg["Section B"]["key3"] = "value3"
To display the resulting configuration, you can try:
import io
output = io.StringIO()
dst_cfg.write(output)
print(output.getvalue())
You get:
[Section A]
key1 = value1
key2 = value2
[Section B]
key3 = value3

After reading this article, I am more familiar with config.ini.
Record as follows:
import io
import configparser
def copy_config_demo():
with io.StringIO() as memory_file:
memory_file.write(str(test_config_data.__doc__)) # original_config.write(memory_file)
memory_file.seek(0)
new_config = configparser.ConfigParser(interpolation=configparser.ExtendedInterpolation())
new_config.read_file(memory_file)
# below is just for test
for section_name, list_item in [(section_name, new_config.items(section_name)) for section_name in new_config.sections()]:
print('\n[' + section_name + ']')
for key, value in list_item:
print(f'{key}: {value}')
def test_config_data():
"""
[Common]
home_dir: /Users
library_dir: /Library
system_dir: /System
macports_dir: /opt/local
[Frameworks]
Python: >=3.2
path: ${Common:system_dir}/Library/Frameworks/
[Arthur]
name: Carson
my_dir: ${Common:home_dir}/twosheds
my_pictures: ${my_dir}/Pictures
python_dir: ${Frameworks:path}/Python/Versions/${Frameworks:Python}
"""
output:
[Common]
home_dir: /Users
library_dir: /Library
system_dir: /System
macports_dir: /opt/local
[Frameworks]
python: >=3.2
path: /System/Library/Frameworks/
[Arthur]
name: Carson
my_dir: /Users/twosheds
my_pictures: /Users/twosheds/Pictures
python_dir: /System/Library/Frameworks//Python/Versions/>=3.2
hoping it is helpful to you.

Related

How we can use SFTPToGCSOperator in GCP composer enviornment(1.10.6)?

Here I want to use SFTPToGCSOperator in composer enviornment(1.10.6) of GCP. I know there is a limitation because The operator present only in latest version of airflow not in composer latest version 1.10.6.
See the refrence -
https://airflow.readthedocs.io/en/latest/howto/operator/gcp/sftp_to_gcs.html
I found the alternative of operator and I created a plugin class, But again I faced the issue for sftphook class, Now I am using older version of sftphook class.
see the below refrence -
from airflow.contrib.hooks.sftp_hook import SFTPHook
https://airflow.apache.org/docs/stable/_modules/airflow/contrib/hooks/sftp_hook.html
I have created a plugin class, later It's import in my DAG script. It's working fine only when we are moveing one file, In that case we need to pass complete file path with extension.
Please refer below example(It's working fine in this scenrio)
DIR = "/test/sftp_dag_test/source_dir"
OBJECT_SRC_1 = "file.csv"
source_path=os.path.join(DIR, OBJECT_SRC_1),
Except this If we are using wildcard, I mean if we want to move all the files from directory I am getting error for get_tree_map method.
Please see below DAG code
import os
from airflow import models
from airflow.models import Variable
from PluginSFTPToGCSOperator import SFTPToGCSOperator
#from airflow.contrib.operators.sftp_to_gcs import SFTPToGCSOperator
from airflow.utils.dates import days_ago
default_args = {"start_date": days_ago(1)}
DIR_path = "/main_dir/sub_dir/"
BUCKET_SRC = "test-gcp-bucket"
with models.DAG(
"dag_sftp_to_gcs", default_args=default_args, schedule_interval=None
) as dag:
copy_sftp_to_gcs = SFTPToGCSOperator(
task_id="t_sftp_to_gcs",
sftp_conn_id="test_sftp_conn",
gcp_conn_id="google_cloud_default",
source_path=os.path.join(DIR_path, "*.gz"),
destination_bucket=BUCKET_SRC,
)
copy_sftp_to_gcs
Here we are using wildcard * in DAG script, please see below plugin class.
import os
from tempfile import NamedTemporaryFile
from typing import Optional, Union
from airflow.plugins_manager import AirflowPlugin
from airflow import AirflowException
from airflow.contrib.hooks.gcs_hook import GoogleCloudStorageHook
from airflow.models import BaseOperator
from airflow.contrib.hooks.sftp_hook import SFTPHook
from airflow.utils.decorators import apply_defaults
WILDCARD = "*"
class SFTPToGCSOperator(BaseOperator):
template_fields = ("source_path", "destination_path", "destination_bucket")
#apply_defaults
def __init__(
self,
source_path: str,
destination_bucket: str = "destination_bucket",
destination_path: Optional[str] = None,
gcp_conn_id: str = "google_cloud_default",
sftp_conn_id: str = "sftp_conn_plugin",
delegate_to: Optional[str] = None,
mime_type: str = "application/octet-stream",
gzip: bool = False,
move_object: bool = False,
*args,
**kwargs
) -> None:
super().__init__(*args, **kwargs)
self.source_path = source_path
self.destination_path = self._set_destination_path(destination_path)
print('destination_bucket : ',destination_bucket)
self.destination_bucket = destination_bucket
self.gcp_conn_id = gcp_conn_id
self.mime_type = mime_type
self.delegate_to = delegate_to
self.gzip = gzip
self.sftp_conn_id = sftp_conn_id
self.move_object = move_object
def execute(self, context):
print("inside execute")
gcs_hook = GoogleCloudStorageHook(
google_cloud_storage_conn_id=self.gcp_conn_id, delegate_to=self.delegate_to
)
sftp_hook = SFTPHook(self.sftp_conn_id)
if WILDCARD in self.source_path:
total_wildcards = self.source_path.count(WILDCARD)
if total_wildcards > 1:
raise AirflowException(
"Only one wildcard '*' is allowed in source_path parameter. "
"Found {} in {}.".format(total_wildcards, self.source_path)
)
print('self.source_path : ',self.source_path)
prefix, delimiter = self.source_path.split(WILDCARD, 1)
print('prefix : ',prefix)
base_path = os.path.dirname(prefix)
print('base_path : ',base_path)
files, _, _ = sftp_hook.get_tree_map(
base_path, prefix=prefix, delimiter=delimiter
)
for file in files:
destination_path = file.replace(base_path, self.destination_path, 1)
self._copy_single_object(gcs_hook, sftp_hook, file, destination_path)
else:
destination_object = (
self.destination_path
if self.destination_path
else self.source_path.rsplit("/", 1)[1]
)
self._copy_single_object(
gcs_hook, sftp_hook, self.source_path, destination_object
)
def _copy_single_object(
self,
gcs_hook: GoogleCloudStorageHook,
sftp_hook: SFTPHook,
source_path: str,
destination_object: str,
) -> None:
"""
Helper function to copy single object.
"""
self.log.info(
"Executing copy of %s to gs://%s/%s",
source_path,
self.destination_bucket,
destination_object,
)
with NamedTemporaryFile("w") as tmp:
sftp_hook.retrieve_file(source_path, tmp.name)
print('before upload self det object : ',self.destination_bucket)
gcs_hook.upload(
self.destination_bucket,
destination_object,
tmp.name,
self.mime_type,
)
if self.move_object:
self.log.info("Executing delete of %s", source_path)
sftp_hook.delete_file(source_path)
#staticmethod
def _set_destination_path(path: Union[str, None]) -> str:
if path is not None:
return path.lstrip("/") if path.startswith("/") else path
return ""
#staticmethod
def _set_bucket_name(name: str) -> str:
bucket = name if not name.startswith("gs://") else name[5:]
return bucket.strip("/")
class SFTPToGCSOperatorPlugin(AirflowPlugin):
name = "SFTPToGCSOperatorPlugin"
operators = [SFTPToGCSOperator]
So this plugin class I am importing in my DAG script and it's wotking fine when we are using file name, Because code is going inside else condition.
But when we are using wildcard we have cursor inside if condition and I am getting error for get_tree_map method.
see below error -
ERROR - 'SFTPHook' object has no attribute 'get_tree_map'
I found the reason of this error this method itself is not present in composer(airflow 1.10.6)-
https://airflow.apache.org/docs/stable/_modules/airflow/contrib/hooks/sftp_hook.html
This method is present in latest version of airflow
https://airflow.readthedocs.io/en/latest/_modules/airflow/providers/sftp/hooks/sftp.html
Now What should I can try, Is there any alternative of this method or any alternative of this operator class.
Does anyone know if there is a solution for this?
Thanks in Advance.
Please ignore Typo or indentation error in stackoverflow. In my code there is no Indentation error.
"providers" packages are only available from Airflow 2.0, which is not yet available in Cloud Composer (as I write this post, the latest available Airflow image is 1.10.14, released this morning).
BUT you can import backport packages which let you enjoy these new packages in earlier versions 1.10.*.
My requirements.txt:
apache-airflow-backport-providers-ssh==2020.10.29
apache-airflow-backport-providers-sftp==2020.10.29
pysftp>=0.2.9
paramiko>=2.6.0
sshtunnel<0.2,>=0.1.4
You can import PyPi packages directly in your Composer environment from the console.
With these dependencies, I could use the newest airflow.providers.ssh.operators.ssh.SSHOperator (formerly airflow.contrib.operators.ssh_operator.SSHOperator) and the new airflow.providers.google.cloud.transfers.gcs_to_sftp.GCSToSFTPOperator (which had no equivalent in contrib operators).
Enjoy!
To use SFTPToGCSOperator in Google Cloud Composer on Airflow version 1.10.6 we need to create a plugin and somehow "hack" Airflow by copying operator/hook codes into one file to enable SFTPToGCSOperator use code from Airflow 1.10.10 version.
The latest Airflow version has a new airflow.providers directory, which does not exist in earlier versions. This is why you saw following error: No module named airflow.providers. All the changes I made are described here:
I prepared working plugin, which you can download here. Before using it, we have to install following PyPI libraries on the Cloud Composer environment: pysftp, paramiko, sshtunnel.
I copied full SFTPToGCSOperator code, which starts in 792nd line. You can see that this operator uses GCSHook:
from airflow.providers.google.cloud.hooks.gcs import GCSHook
which also need to be copied to the plugin - starts in 193rd line.
Then, GCSHook inherits from GoogleBaseHook class, which we can change for GoogleCloudBaseHook accessible in Airflow 1.10.6 version, and import it:
from airflow.contrib.hooks.gcp_api_base_hook import GoogleCloudBaseHook
Finally, there is a need to import SFTPHook code into the plugin - starts in 39th line, which inherits from SSHHook class, we can use one from Airflow 1.10.6 version by changing import statement:
from airflow.contrib.hooks.ssh_hook import SSHHook
At the end of file, you can find the definition of the plugin:
class SFTPToGCSOperatorPlugin(AirflowPlugin):
name = "SFTPToGCSOperatorPlugin"
operators = [SFTPToGCSOperator]
Plugin creation is needed, as an Airflow built-in operator is not currently available in Airflow 1.10.6 version (the latest in Cloud Composer). You can keep an eye on Cloud Composer version lists in order to see when the newest version of Airflow will be available to use.
I hope you find the above pieces of information useful.

Reading multiple files in a directory with pyyaml

I'm trying to read all yaml files in a directory, but I am having trouble. First, because I am using Python 2.7 (and I cannot change to 3) and all of my files are utf-8 (and I also need them to keep this way).
import os
import yaml
import codecs
def yaml_reader(filepath):
with codecs.open(filepath, "r", encoding='utf-8') as file_descriptor:
data = yaml.load_all(file_descriptor)
return data
def yaml_dump(filepath, data):
with open(filepath, 'w') as file_descriptor:
yaml.dump(data, file_descriptor)
if __name__ == "__main__":
filepath = os.listdir(os.getcwd())
data = yaml_reader(filepath)
print data
When I run this code, python gives me the message:
TypeError: coercing to Unicode: need string or buffer, list found.
I want this program to show the content of the files. Can anyone help me?
I guess the issue is with filepath.
os.listdir(os.getcwd()) returns the list of all the files in the directory. so you are passing the list to codecs.open() instead of filename
There are multiple problems with your code, apart from that it is invalide Python, in the way you formatted this.
def yaml_reader(filepath):
with codecs.open(filepath, "r", encoding='utf-8') as file_descriptor:
data = yaml.load_all(file_descriptor)
return data
however it is not necessary to do the decoding, PyYAML is perfectly capable of processing UTF-8:
def yaml_reader(filepath):
with open(filepath, "rb") as file_descriptor:
data = yaml.load_all(file_descriptor)
return data
I hope you realise your trying to load multiple documents and always get a list as a result in data even if your file contains one document.
Then the line:
filepath = os.listdir(os.getcwd())
gives you a list of files, so you need to do:
filepath = os.listdir(os.getcwd())[0]
or decide in some other way, which of the files you want to open. If you want to combine all files (assuming they are YAML) in one big YAML file, you need to do:
if __name__ == "__main__":
data = []
for filepath in os.listdir(os.getcwd()):
data.extend(yaml_reader(filepath))
print data
And your dump routine would need to change to:
def yaml_dump(filepath, data):
with open(filepath, 'wb') as file_descriptor:
yaml.dump(data, file_descriptor, allow_unicode=True, encoding='utf-8')
However this all brings you to the biggest problem: that you are using PyYAML, that will mangle your YAML, dropping flow-style, comment, anchor names, special int/float, quotes around scalars etc. Apart from that PyYAML has not been updated to support YAML 1.2 documents (which has been the standard since 2009). I recommend you switch to using ruamel.yaml (disclaimer: I am the author of that package), which supports YAML 1.2 and leaves comments etc in place.
And even if you are bound to use Python 2, you should use the Python 3 like syntax e.g. for print that you can get with from __future__ imports.
So I recommend you do:
pip install pathlib2 ruamel.yaml
and then use:
from __future__ import absolute_import, unicode_literals, print_function
from pathlib import Path
from ruamel.yaml import YAML
if __name__ == "__main__":
data = []
yaml = YAML()
yaml.preserve_quotes = True
for filepath in Path('.').glob('*.yaml'):
data.extend(yaml.load_all(filepath))
print(data)
yaml.dump(data, Path('your_output.yaml'))

Saving data from traceplot in PyMC3

Below is the code for a simple Bayesian Linear regression. After I obtain the trace and the plots for the parameters, is there any way in which I can save the data that created the plots in a file so that if I need to plot it again I can simply plot it from the data in the file rather than running the whole simulation again?
import pymc3 as pm
import matplotlib.pyplot as plt
import numpy as np
x = np.linspace(0,9,5)
y = 2*x + 5
yerr=np.random.rand(len(x))
def soln(x, p1, p2):
return p1+p2*x
with pm.Model() as model:
# Define priors
intercept = pm.Normal('Intercept', 15, sd=5)
slope = pm.Normal('Slope', 20, sd=5)
# Model solution
sol = soln(x, intercept, slope)
# Define likelihood
likelihood = pm.Normal('Y', mu=sol,
sd=yerr, observed=y)
# Sampling
trace = pm.sample(1000, nchains = 1)
pm.traceplot(trace)
print pm.summary(trace, ['Slope'])
print pm.summary(trace, ['Intercept'])
plt.show()
There are two easy ways of doing this:
Use a version after 3.4.1 (currently this means installing from master, with pip install git+https://github.com/pymc-devs/pymc3). There is a new feature that allows saving and loading traces efficiently. Note that you need access to the model that created the trace:
...
pm.save_trace(trace, 'linreg.trace')
# later
with model:
trace = pm.load_trace('linreg.trace')
Use cPickle (or pickle in python 3). Note that pickle is at least a little insecure, don't unpickle data from untrusted sources:
import cPickle as pickle # just `import pickle` on python 3
...
with open('trace.pkl', 'wb') as buff:
pickle.dump(trace, buff)
#later
with open('trace.pkl', 'rb') as buff:
trace = pickle.load(buff)
Update for someone like me who is still coming over to this question:
load_trace and save_trace functions were removed. Since version 4.0 even the deprecation waring for these functions were removed.
The way to do it is now to use arviz:
with model:
trace = pymc.sample(return_inferencedata=True)
trace.to_netcdf("filename.nc")
And it can be loaded with:
trace = arviz.from_netcdf("filename.nc")
This way works for me :
# saving trace
pm.save_trace(trace=trace_nb, directory=r"c:\Users\xxx\Documents\xxx\traces\trace_nb")
# loading saved traces
with model_nb:
t_nb = pm.load_trace(directory=r"c:\Users\xxx\Documents\xxx\traces\trace_nb")

How do I import files from other directory in python 2.7

I have been experimenting with python by creating some programs .The thing is, I have no idea how to import something OUT of the default python directory.
OK
So I did some heavy research and the conclusion is
if u want to access a file saved at different location
use
f = open('E:/somedir/somefile.txt', 'r')
r = f.read()
NOTE: Dont use '\' that were I went wrong.Our system addresses uses '\' So be careful
If you need to just read in a file and not import a module the documentation covers this extensively.
https://docs.python.org/2/tutorial/inputoutput.html#reading-and-writing-files
Specifically for Windows file systems you will need to do one of the following:
1.) Use forwardslashes vs backslashes. This should work with most OSes.
f = open("c:/somedir/somefile.txt", "r")
2.) Use a raw string.
f = open(r"c:\somedir\somefile.txt", "r")
3.) Escape the backslashes.
f = open("c:\\somedir\\somefile.txt", "r")
If you need to import a module to use in your program from outside your programs directory you can use the below information.
Python looks in the sys.path to see if the module exists there and if so does the import. If the path where you files/modules are located is not in the sys.path, Python will raise an ImportError. You can update the path programmatically by using the sys module.
import sys
dir = "path to mymodule"
if dir not in sys.path:
sys.path.append(dir)
import mymodule
You can check the current sys.path by using:
print(sys.path)
Example:
>>> print(sys.path)
['', '/Library/Frameworks/Python.framework/Versions/3.4/lib/python34.zip', '/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4', '/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/plat-darwin', '/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/lib-dynload', '/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages']
>>> sys.path.append("/Users/ddrummond/pymodules")
>>> print(sys.path)
['', '/Library/Frameworks/Python.framework/Versions/3.4/lib/python34.zip', '/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4', '/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/plat-darwin', '/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/lib-dynload', '/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages', '/Users/ddrummond/pymodules']
>>>
You can see that sys.path now contains '/Users/ddrummond/pymodules'.

Program for Backup - Python

Im trying to execute the following code in Python 2.7 on Windows7. The purpose of the code is to take back up from the specified folder to a specified folder as per the naming pattern given.
However, Im not able to get it work. The output has always been 'Backup Failed'.
Please advise on how I get resolve this to get the code working.
Thanks.
Code :
backup_ver1.py
import os
import time
import sys
sys.path.append('C:\Python27\GnuWin32\bin')
source = 'C:\New'
target_dir = 'E:\Backup'
target = target_dir + os.sep + time.strftime('%Y%m%d%H%M%S') + '.zip'
zip_command = "zip -qr {0} {1}".format(target,''.join(source))
print('This is a program for backing up files')
print(zip_command)
if os.system(zip_command)==0:
print('Successful backup to', target)
else:
print('Backup FAILED')
See if escaping the \'s helps :-
source = 'C:\\New'
target_dir = 'E:\\Backup'