import matplotlib.dates as mdates
plt.gca().xaxis.set_major_formatter(mdates.DateFormatter('%H:%M'))
25
Feb
2022
Programming languages
25
Feb
2022
How to change matplotlib X axis timestamp format
Sometimes you get weird timestamp format choices in Matplotlib such as 22 19:40 (meaning 19:40 o’clock on the 22nd of whatever month).
This is easy to fix:
import matplotlib.dates as mdates
plt.gca().xaxis.set_major_formatter(mdates.DateFormatter('%H:%M'))which will result in this image, for example:
15
Feb
2022
How to get first day of next month in Javascript using DayJS
See the dayjs docs for more info about the library.
const now = dayjs(); const nextMonth = now.month(now.month() + 1).date(1).hour(0).minute(0).second(0); // Example usage console.info(nextMonth.format()) // Prints, for example, "2022-03-01T00:00:00+01:00"
This will also work in december as DayJS processes month(13) correctly:
const now = dayjs('2021-12-09');
const nextMonth = now.month(now.month() + 1).date(1).hour(0).minute(0).second(0);
// This prints '2022-01-01T00:00:00+01:00'
console.info(nextMonth.format());
13
Feb
2022
How to reverse std::string using std::reverse (C++)
#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
int main(int argc, char** argv) {
std::string s = "My string";
// This reverses s in-place.
std::reverse(std::begin(s), std::end(s));
// Prints "gnirts yM"
cout << s << endl;
}
13
Feb
2022
re2 C++ replace (GlobalReplace) minimal example
This minimal example shows how to replace strings using the re2 GlobalReplace() function:
#include <re2/re2.h>
#include <iostream>
#include <string>
using namespace re2;
using namespace std;
// Pre-compiled regex
RE2 myRegex("\\$[^\\$]+\\$");
int main(int argc, char** argv) {
string myString = "This string $abc123$ contains two formulas $123 != 456$.";
// NOTE: This will modify myString!
RE2::GlobalReplace(&myString, myRegex, "FORMULA");
// Prints "This string FORMULA contains two formulas FORMULA."
cout << myString << endl;
}
13
Feb
2022
re2 C++ regular expressions library: How to #include?
#include <re2/re2.h> using namespace re2;
13
Feb
2022
cpp-httplib: How to get query parameters
This example shows how to get a query parameter in cpp-httplib. See the cpp-httplib hello example for the full source code:
svr.Get("/hi", [](const httplib::Request& req, httplib::Response& res) {
std::string id = req.get_param_value("id");
res.set_content("id=" + id, "text/plain");
});Access it at http://localhost:8080/hi?id=myid
and it will show you
id=myid
id will be empty (== "") if no such parameter is given.
12
Feb
2022
How to fix Paho MQTT undefined reference to `SHA1_Init’
Problem:
When trying to build your C++ application using Paho MQTT, you see a bunch of undefined reference error messages:
MQTTAsync.c:(.text+0x3482): undefined reference to `OpenSSL_version' /usr/bin/ld: MQTTAsync.c:(.text+0x34a1): undefined reference to `OpenSSL_version' /usr/bin/ld: MQTTAsync.c:(.text+0x34c0): undefined reference to `OpenSSL_version' /usr/bin/ld: MQTTAsync.c:(.text+0x34df): undefined reference to `OpenSSL_version' /usr/bin/ld: MQTTAsync.c:(.text+0x34fe): undefined reference to `OpenSSL_version' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(MQTTAsyncUtils.c.o): in function `MQTTAsync_closeOnly': MQTTAsyncUtils.c:(.text+0x9b6): undefined reference to `SSL_SESSION_free' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(MQTTAsyncUtils.c.o): in function `MQTTAsync_receiveThread': MQTTAsyncUtils.c:(.text+0x463b): undefined reference to `SSL_set_session' /usr/bin/ld: MQTTAsyncUtils.c:(.text+0x5255): undefined reference to `SSL_get1_session' /usr/bin/ld: MQTTAsyncUtils.c:(.text+0x55bb): undefined reference to `SSL_get1_session' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `call_ssl_psk_cb': SSLSocket.c:(.text+0x11b): undefined reference to `SSL_get_SSL_CTX' /usr/bin/ld: SSLSocket.c:(.text+0x129): undefined reference to `SSL_CTX_get_ex_data' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_error': SSLSocket.c:(.text+0x1fa): undefined reference to `SSL_get_error' /usr/bin/ld: SSLSocket.c:(.text+0x22d): undefined reference to `ERR_print_errors_cb' /usr/bin/ld: SSLSocket.c:(.text+0x2f1): undefined reference to `ERR_get_error' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSL_CTX_info_callback': SSLSocket.c:(.text+0x376): undefined reference to `SSL_alert_desc_string_long' /usr/bin/ld: SSLSocket.c:(.text+0x381): undefined reference to `SSL_alert_type_string_long' /usr/bin/ld: SSLSocket.c:(.text+0x3bc): undefined reference to `SSL_get_verify_result' /usr/bin/ld: SSLSocket.c:(.text+0x411): undefined reference to `SSL_state_string_long' /usr/bin/ld: SSLSocket.c:(.text+0x461): undefined reference to `SSL_get_current_cipher' /usr/bin/ld: SSLSocket.c:(.text+0x469): undefined reference to `SSL_CIPHER_get_name' /usr/bin/ld: SSLSocket.c:(.text+0x474): undefined reference to `SSL_state_string_long' /usr/bin/ld: SSLSocket.c:(.text+0x4d1): undefined reference to `SSL_alert_desc_string_long' /usr/bin/ld: SSLSocket.c:(.text+0x4dc): undefined reference to `SSL_alert_type_string_long' /usr/bin/ld: SSLSocket.c:(.text+0x4e7): undefined reference to `SSL_state_string_long' /usr/bin/ld: SSLSocket.c:(.text+0x503): undefined reference to `SSL_alert_desc_string_long' /usr/bin/ld: SSLSocket.c:(.text+0x50e): undefined reference to `SSL_alert_type_string_long' /usr/bin/ld: SSLSocket.c:(.text+0x541): undefined reference to `SSL_alert_desc_string_long' /usr/bin/ld: SSLSocket.c:(.text+0x54c): undefined reference to `SSL_alert_type_string_long' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_initialize': SSLSocket.c:(.text+0x8ee): undefined reference to `OPENSSL_init_ssl' /usr/bin/ld: SSLSocket.c:(.text+0x90a): undefined reference to `OPENSSL_init_crypto' /usr/bin/ld: SSLSocket.c:(.text+0x916): undefined reference to `OPENSSL_init_ssl' /usr/bin/ld: SSLSocket.c:(.text+0x922): undefined reference to `OPENSSL_init_crypto' /usr/bin/ld: SSLSocket.c:(.text+0xa11): undefined reference to `CRYPTO_get_ex_new_index' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_createContext': SSLSocket.c:(.text+0xbee): undefined reference to `SSL_CTX_use_certificate_chain_file' /usr/bin/ld: SSLSocket.c:(.text+0xc48): undefined reference to `SSL_CTX_set_default_passwd_cb' /usr/bin/ld: SSLSocket.c:(.text+0xc55): undefined reference to `SSL_CTX_set_default_passwd_cb_userdata' /usr/bin/ld: SSLSocket.c:(.text+0xc67): undefined reference to `SSL_CTX_use_PrivateKey_file' /usr/bin/ld: SSLSocket.c:(.text+0xc9a): undefined reference to `SSL_CTX_load_verify_locations' /usr/bin/ld: SSLSocket.c:(.text+0xce5): undefined reference to `SSL_CTX_set_default_verify_paths' /usr/bin/ld: SSLSocket.c:(.text+0xd2e): undefined reference to `SSL_CTX_set_cipher_list' /usr/bin/ld: SSLSocket.c:(.text+0xd56): undefined reference to `SSL_CTX_set_ex_data' /usr/bin/ld: SSLSocket.c:(.text+0xd66): undefined reference to `SSL_CTX_set_psk_client_callback' /usr/bin/ld: SSLSocket.c:(.text+0xd8f): undefined reference to `SSL_CTX_ctrl' /usr/bin/ld: SSLSocket.c:(.text+0xdc5): undefined reference to `SSL_CTX_free' /usr/bin/ld: SSLSocket.c:(.text+0xe51): undefined reference to `SSL_CTX_set_alpn_protos' /usr/bin/ld: SSLSocket.c:(.text+0xeb9): undefined reference to `TLS_client_method' /usr/bin/ld: SSLSocket.c:(.text+0xec1): undefined reference to `SSL_CTX_new' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_setSocketForSSL': SSLSocket.c:(.text+0x1046): undefined reference to `SSL_CTX_set_info_callback' /usr/bin/ld: SSLSocket.c:(.text+0x1056): undefined reference to `SSL_CTX_set_msg_callback' /usr/bin/ld: SSLSocket.c:(.text+0x1075): undefined reference to `SSL_new' /usr/bin/ld: SSLSocket.c:(.text+0x10ab): undefined reference to `SSL_get_cipher_list' /usr/bin/ld: SSLSocket.c:(.text+0x10be): undefined reference to `SSL_set_fd' /usr/bin/ld: SSLSocket.c:(.text+0x113b): undefined reference to `SSL_ctrl' /usr/bin/ld: SSLSocket.c:(.text+0x121c): undefined reference to `SSL_CTX_set_verify' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_connect': SSLSocket.c:(.text+0x12b7): undefined reference to `ERR_clear_error' /usr/bin/ld: SSLSocket.c:(.text+0x12bf): undefined reference to `SSL_connect' /usr/bin/ld: SSLSocket.c:(.text+0x135d): undefined reference to `SSL_get_peer_certificate' /usr/bin/ld: SSLSocket.c:(.text+0x138c): undefined reference to `X509_check_host' /usr/bin/ld: SSLSocket.c:(.text+0x13d4): undefined reference to `CRYPTO_free' /usr/bin/ld: SSLSocket.c:(.text+0x13f6): undefined reference to `X509_free' /usr/bin/ld: SSLSocket.c:(.text+0x144d): undefined reference to `X509_check_ip_asc' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_getch': SSLSocket.c:(.text+0x1569): undefined reference to `ERR_clear_error' /usr/bin/ld: SSLSocket.c:(.text+0x1579): undefined reference to `SSL_read' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_destroyContext': SSLSocket.c:(.text+0x1630): undefined reference to `SSL_CTX_free' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_close': SSLSocket.c:(.text+0x16b8): undefined reference to `ERR_clear_error' /usr/bin/ld: SSLSocket.c:(.text+0x16c1): undefined reference to `SSL_shutdown' /usr/bin/ld: SSLSocket.c:(.text+0x16ce): undefined reference to `SSL_free' /usr/bin/ld: SSLSocket.c:(.text+0x16fd): undefined reference to `SSL_CTX_free' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_putdatas': SSLSocket.c:(.text+0x191f): undefined reference to `ERR_clear_error' /usr/bin/ld: SSLSocket.c:(.text+0x1930): undefined reference to `SSL_write' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_getdata': SSLSocket.c:(.text+0x1ca5): undefined reference to `ERR_clear_error' /usr/bin/ld: SSLSocket.c:(.text+0x1cb8): undefined reference to `SSL_read' /usr/bin/ld: SSLSocket.c:(.text+0x1d7f): undefined reference to `SSL_pending' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_continueWrite': SSLSocket.c:(.text+0x1e2f): undefined reference to `ERR_clear_error' /usr/bin/ld: SSLSocket.c:(.text+0x1e3f): undefined reference to `SSL_write' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(Base64.c.o): in function `Base64_encodeDecode.part.0': Base64.c:(.text+0x1f): undefined reference to `BIO_f_base64' /usr/bin/ld: Base64.c:(.text+0x27): undefined reference to `BIO_new' /usr/bin/ld: Base64.c:(.text+0x2f): undefined reference to `BIO_s_mem' /usr/bin/ld: Base64.c:(.text+0x37): undefined reference to `BIO_new' /usr/bin/ld: Base64.c:(.text+0x45): undefined reference to `BIO_push' /usr/bin/ld: Base64.c:(.text+0x55): undefined reference to `BIO_set_flags' /usr/bin/ld: Base64.c:(.text+0x78): undefined reference to `BIO_write' /usr/bin/ld: Base64.c:(.text+0x8e): undefined reference to `BIO_ctrl' /usr/bin/ld: Base64.c:(.text+0x9e): undefined reference to `BIO_free_all' /usr/bin/ld: Base64.c:(.text+0xc1): undefined reference to `BIO_read' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(WebSocket.c.o): in function `WebSocket_buildFrame.constprop.0': WebSocket.c:(.text+0x441): undefined reference to `RAND_bytes' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(WebSocket.c.o): in function `uuid_generate': WebSocket.c:(.text+0x721): undefined reference to `RAND_bytes' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(WebSocket.c.o): in function `WebSocket_connect': WebSocket.c:(.text+0x929): undefined reference to `RAND_bytes' /usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(WebSocket.c.o): in function `WebSocket_upgrade': WebSocket.c:(.text+0x1dd9): undefined reference to `SHA1_Init' /usr/bin/ld: WebSocket.c:(.text+0x1def): undefined reference to `SHA1_Update' /usr/bin/ld: WebSocket.c:(.text+0x1dff): undefined reference to `SHA1_Final' collect2: error: ld returned 1 exit status
Solution
In addition to linking the Paho MQTT libraries, you also need to link OpenSSL, i.e. the ssl and crypto libraries. You can link them, for example using
target_link_libraries(myexecutable ssl crypto)
in CMake or by adding these linker flags for GCC:
-lssl -lcrypto
12
Feb
2022
How to link Paho MQTT C++ binding using CMake
target_link_libraries(myexecutable paho-mqttpp3 paho-mqtt3as ssl crypto)
12
Feb
2022
How to initialize new C++ executable project using conan 1.x
Important note: This post is for Conan 1.x and is not compatible with the current version conan 2.x! See How to initialize C++ project using conan 2.x for an updated version of this post!
In the directory where you want to create the project, run (obviously, replace mypackageby the name of everywhere in our code!)
conan new mypackage/1.0.0 -s
-s is important here. It tells conan that the source is available in the project directory and it should not be pulled using git etc.
This will initialize a shared library project, which we will now modify to build an executable.
First, open src/CMakeLists.txt and change add_library() to add_executable(), for example
add_library(mypackage mypackage.cpp)
to
add_executable(mypackage mypackage.cpp)
Now we shall modify conanfile.py to properly build & install the executable:
def package(self):
self.copy("*.h", dst="include", src="src")
self.copy("*.lib", dst="lib", keep_path=False)
self.copy("*.dll", dst="bin", keep_path=False)
self.copy("*.dylib*", dst="lib", keep_path=False)
self.copy("*.so", dst="lib", keep_path=False)
self.copy("*.a", dst="lib", keep_path=False)
def package_info(self):
self.cpp_info.libs = ["NoxecoDB"]
with
def package(self):
self.copy("mypackage", src="bin", dst="bin", keep_path=False)
def package_info(self):
self.env_info.PATH = os.path.join(self.package_folder, "bin")
def deploy(self):
self.copy("mypackage", dst="bin", src="bin")
and add
import os.path
to the top of the file
Now let’s add a main() function to src/mypackage.cpp. Replace the file’s content with
#include <iostream>
int main(int argc, char** argv) {
std::cout << "Hello World!" <<std::endl;
}
Now it’s time to install the dependencies & build the project using
conan install . && conan build .
The executable will be in
bin/mypackage
You can run it using
./bin/mypackage
which will print
Hello World!
I also recommend to add this .gitignore:
CMakeCache.txt CMakeFiles/ Makefile bin/ cmake_install.cmake conan.lock conanbuildinfo.cmake conanbuildinfo.txt conaninfo.txt graph_info.json
08
Feb
2022
LinuxCNC: How to get current position including offset using Python
In our previous example LinuxCNC: How to find current position using Python we showed how to use stat.actual_position to get the current position in machine coordinates using LinuxCNC’s Python API.
#!/usr/bin/env python2.7 import linuxcnc stat = linuxcnc.stat() stat.poll() x,y,z,a,b,c,u,v,w = stat.actual_position # NOTE: Ignore ABCUVW since not used for my machine # Subtract G5x offset xo,yo,zo,ao,bo,co,uo,vo,wo = stat.g5x_offset x -= xo y -= yo z -= zo # Subtract tool offset xo,yo,zo,ao,bo,co,uo,vo,wo = stat.tool_offset x -= xo y -= yo z -= zo # Print offset coordinates print(x,y,z)
08
Feb
2022
LinuxCNC: What attributes can you read from a linuxcnc.stat() object?
As shown in our previous example LinuxCNC: How to find current position using Python you can get an
These are the attributes of the object returned by linuxcnc.stat() for LinuxCNC 2.7:
acceleration active_queue actual_position adaptive_feed_enabled ain angular_units aout axes axis axis_mask block_delete call_level command current_line current_vel cycle_time debug delay_left din distance_to_go dout dtg echo_serial_number enabled estop exec_state feed_hold_enabled feed_override_enabled feedrate file flood g5x_index g5x_offset g92_offset gcodes homed id inpos input_timeout interp_state interpreter_errcode joint_actual_position joint_position kinematics_type limit linear_units lube lube_level max_acceleration max_velocity mcodes mist motion_line motion_mode motion_type optional_stop paused pocket_prepped poll position probe_tripped probe_val probed_position probing program_units queue queue_full queued_mdi_commands rapidrate read_line rotation_xy settings spindle_brake spindle_direction spindle_enabled spindle_increasing spindle_override_enabled spindle_speed spindlerate state task_mode task_paused task_state tool_in_spindle tool_offset tool_table velocity
You can find those out using
#!/usr/bin/env python2.7
import linuxcnc
stat = linuxcnc.stat()
stat.poll()
for entry in dir(stat):
print(entry)
08
Feb
2022
LinuxCNC: How to find current position using Python
This will show the position in machine coordinates such as
#!/usr/bin/env python2.7 import linuxcnc stat = linuxcnc.stat() stat.poll() print(stat.actual_position)
Example output:
(7.4023762662053105, 26.443582149595567, 297.289833343029, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0)
08
Feb
2022
LinuxCNC: Custom M-100 G-Code that logs time, parameters & filename to CSV
Place this file in e.g. linuxcnc/configs/myCNC/custom-mcode/M100
#!/usr/bin/env python2.7
# M100: write timestamp, parameters and gcode filename to linuxcnc/logM100.txt
import sys
import linuxcnc
from datetime import datetime
dt = datetime.now()
stat = linuxcnc.stat() # create a connection to the status channel
stat.poll()
with open("/home/cnc/linuxcnc/logM100.txt", "a") as outfile:
outfile.write("{} | Args={} | Path={}\n".format(dt.isoformat(), ", ".join(sys.argv[1:]), stat.file))and make executable using
chmod a+x ./linuxcnc/configs/myCNC/custom-mcodes/M100
08
Feb
2022
LinuxCNC: How to read current position in Python and log to CSV
Also see our post on how to just read the position especially if you don’t care about the CSV logging: LinuxCNC: How to find current position using Python
This script will log the position to CSV approximately every millisecond. The position will be logged in machine coordinates.
#!/usr/bin/env python2.7
import linuxcnc
import datetime
import time
stat = linuxcnc.stat()
with open("position-log.csv", "w") as outfile:
while True:
dt = datetime.datetime.now()
stat.poll()
x,y,z,a,b,c,u,v,w = stat.actual_position
outfile.write("{},{:.4f},{:.4f},{:.4f}\n".format(dt.isoformat(), x, y, z))
time.sleep(0.001)
08
Feb
2022
How to parse linuxcnc.var using Python
with open("/home/cnc/linuxcnc/configs/myCNC/linuxcnc.var") as infile:
lines = infile.readlines()
splitted = [line.strip().partition("\t") for line in lines]
linuxCNCVar = {int(splitResult[0]): float(splitResult[-1]) for splitResult in splitted}Example output for linuxCNCVar:
{5161: 0.0,
5162: 0.0,
5163: 0.0,
5164: 0.0,
5165: 0.0,
5166: 0.0,
5167: 0.0,
5168: 0.0,
5169: 0.0,
5181: 0.0,
5182: 0.0,
5183: 0.0,
5184: 0.0,
5185: 0.0,
5186: 0.0,
5187: 0.0,
5188: 0.0,
5189: 0.0,
5210: 0.0,
5211: 0.0,
5212: 0.0,
5213: 0.0,
5214: 0.0,
5215: 0.0,
5216: 0.0,
5217: 0.0,
5218: 0.0,
5219: 0.0,
5220: 1.0,
5221: 7.40119,
5222: 13.549249,
5223: 298.476583,
5224: 0.0,
5225: 0.0,
5226: 0.0,
5227: 0.0,
5228: 0.0,
5229: 0.0,
5230: 0.0,
5241: 36.868548,
5242: 141.752329,
5243: 207.563262,
5244: 0.0,
5245: 0.0,
5246: 0.0,
5247: 0.0,
5248: 0.0,
5249: 0.0,
5250: 0.0,
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03
Feb
2022
How to fix tox AttributeError: module ‘virtualenv.create.via_global_ref.builtin.cpython.mac_os’ has no attribute ‘CPython2macOsArmFramework’
Problem:
While trying to run Python tests using tox, you see an error message like
GLOB sdist-make: /home/uli/dev/UliEngineering/setup.py py37 create: /home/uli/dev/UliEngineering/.tox/py37 ERROR: InterpreterNotFound: python3.7 py38 create: /home/uli/dev/UliEngineering/.tox/py38 ERROR: invocation failed (exit code 1), logfile: /home/uli/dev/UliEngineering/.tox/py38/log/py38-0.log ========================================================================================= log start ========================================================================================= AttributeError: module 'virtualenv.create.via_global_ref.builtin.cpython.mac_os' has no attribute 'CPython2macOsArmFramework' ========================================================================================== log end ========================================================================================== ERROR: InvocationError for command /usr/bin/python3 -m virtualenv --no-download --python /usr/bin/python3 py38 (exited with code 1) __________________________________________________________________________________________ summary __________________________________________________________________________________________ ERROR: py37: InterpreterNotFound: python3.7 ERROR: py38: InvocationError for command /usr/bin/python3 -m virtualenv --no-download --python /usr/bin/python3 py38 (exited with code 1)
Solution:
This error occurs because two different and incompatible version of virtualenv are installed.
First, uninstall all versions using these commands:
First run as user (not as root) to uninstall any locally installed package in ~/.local:
pip3 uninstall virtualenv
Then, uninstall global packages
sudo pip3 uninstall virtualenv
Now uninstall the apt package on Debian/Ubuntu (uninstall using your package manager for other distros):
sudo apt purge python3-virtualenv
Now it’s time to install one version of virtualenv:
sudo pip3 install virtualenv
After that, you can try running tox again.
02
Feb
2022
Create a numpy array of one datetime64 per day and mark the start of the month
startdate = np.datetime64('2022-01-01T00:00:00.000000')
# 10000 days. This array contains 0 (Day 0), 1 (Day 1), etc
day_offsets = np.arange(10000, dtype=np.int64)
usec_per_day = int(1e6) * 86400 # 86.4k sec per day, 1e6 microseconds per second
# Compute microseconds offset from first day
usec_offsets = day_offsets * usec_per_day
# Compute timestamps
timestamps = startdate + usec_offsets
# Mark start of month in boolean array
is_start_of_month = np.zeros_like(timestamps, dtype=bool)
for index, timestamp in np.ndenumerate(timestamps):
is_start_of_month[index[0]] = timestamp.astype(datetime).day == 1Using this method, timestamps will be the start of each day
array(['2022-01-01T00:00:00.000000', '2022-01-02T00:00:00.000000',
'2022-01-03T00:00:00.000000', ..., '2101-12-30T00:00:00.000000',
'2101-12-31T00:00:00.000000', '2102-01-01T00:00:00.000000'],
dtype='datetime64[us]')
02
Feb
2022
Pandas: How to apply numpy function to every column
You can use df.transform(func, axis=0) to apply a numpy function. This leverages the fact that numpy functions work with pandas Series objects.
Example based on How to create pandas time series DataFrame example dataset:
# Load pre-built time series example dataset
df = pd.read_csv("https://datasets.techoverflow.net/timeseries-example.csv", parse_dates=["Timestamp"])
df.set_index("Timestamp", inplace=True)
# np.square will be called individually for each column
new_df = df.transform(np.square, axis=0)
Output
Original time series:
Squared time series:
Full example code
import numpy as np
import pandas as pd
from matplotlib import pyplot as plt
# Load pre-built time series example dataset
df = pd.read_csv("https://datasets.techoverflow.net/timeseries-example.csv", parse_dates=["Timestamp"])
df.set_index("Timestamp", inplace=True)
# np.sqrt will be called individually for each column
new_df = df.transform(np.square, axis=0)
# Plot subsection of original DF for better visibility
df.iloc[:len(df)//2].plot()
plt.gcf().set_size_inches(10,5)
plt.savefig("Normal-Timeseries.svg")
# Plot subsection of transformed DF for better visibility
new_df.iloc[:len(df)//2].plot()
plt.gcf().set_size_inches(10,5)
plt.savefig("Square-Timeseries.svg")
02
Feb
2022
Numpy nth root: How to
To find the nth root of number or array x in numpy use:
np.power(x, (1/n))
n can be a natural number like 4 but it can also be a floating point number like 3.26.
Example: Compute the 78th root of 1.234
>>> import numpy as np >>> np.power(1.234, (1/78)) 1.0026992894299456