Copy a Python dictionary N times into a list

Question

Lets say I have a dictionary and list like the below:

l: list = [1,2,3,4]
d: dict = {"Hello": "World"}

I want to copy this dictionary exactly len(l) times.

I want to eventually create a list of tuples that looks like:

[(1, {"Hello": "World"}),(2, {"Hello": "World"}),(3, {"Hello": "World"}),(4, {"Hello": "World"})]

To create this I imagine I could do:

output: list = list(zip(l, repeated_dicts))

but need to replicate the dictionary the specified number of times in the list.

I tried using itertools.islice and itertools.cycle but couldn't quite get it. Any ideas?

Answer 1

This problem is caused by the new PathPatternParser introduced in Spring Boot 2.6. There are two ways to resolve:

As suggested by @gsan in the comment, add following in your application.yml or application.properties:

spring.mvc.pathmatch.matching-strategy=ant_path_matcher

OR

Add the following bean in your config class:

import org.springframework.boot.actuate.autoconfigure.endpoint.web.CorsEndpointProperties;
import org.springframework.boot.actuate.autoconfigure.endpoint.web.WebEndpointProperties;
import org.springframework.boot.actuate.autoconfigure.web.server.ManagementPortType;
import org.springframework.boot.actuate.endpoint.ExposableEndpoint;
import org.springframework.boot.actuate.endpoint.web.EndpointLinksResolver;
import org.springframework.boot.actuate.endpoint.web.EndpointMapping;
import org.springframework.boot.actuate.endpoint.web.EndpointMediaTypes;
import org.springframework.boot.actuate.endpoint.web.ExposableWebEndpoint;
import org.springframework.boot.actuate.endpoint.web.WebEndpointsSupplier;
import org.springframework.boot.actuate.endpoint.web.annotation.ControllerEndpointsSupplier;
import org.springframework.boot.actuate.endpoint.web.annotation.ServletEndpointsSupplier;
import org.springframework.boot.actuate.endpoint.web.servlet.WebMvcEndpointHandlerMapping;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
import org.springframework.util.StringUtils;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

@Bean
public WebMvcEndpointHandlerMapping webEndpointServletHandlerMapping(WebEndpointsSupplier webEndpointsSupplier,
        ServletEndpointsSupplier servletEndpointsSupplier, ControllerEndpointsSupplier controllerEndpointsSupplier,
        EndpointMediaTypes endpointMediaTypes, CorsEndpointProperties corsProperties,
        WebEndpointProperties webEndpointProperties, Environment environment) {
    List<ExposableEndpoint<?>> allEndpoints = new ArrayList();
    Collection<ExposableWebEndpoint> webEndpoints = webEndpointsSupplier.getEndpoints();
    allEndpoints.addAll(webEndpoints);
    allEndpoints.addAll(servletEndpointsSupplier.getEndpoints());
    allEndpoints.addAll(controllerEndpointsSupplier.getEndpoints());
    String basePath = webEndpointProperties.getBasePath();
    EndpointMapping endpointMapping = new EndpointMapping(basePath);
    boolean shouldRegisterLinksMapping = this.shouldRegisterLinksMapping(webEndpointProperties, environment,
            basePath);
    return new WebMvcEndpointHandlerMapping(endpointMapping, webEndpoints, endpointMediaTypes,
            corsProperties.toCorsConfiguration(), new EndpointLinksResolver(allEndpoints, basePath),
            shouldRegisterLinksMapping, null);
}

private boolean shouldRegisterLinksMapping(WebEndpointProperties webEndpointProperties, Environment environment,
        String basePath) {
    return webEndpointProperties.getDiscovery().isEnabled() && (StringUtils.hasText(basePath)
        || ManagementPortType.get(environment).equals(ManagementPortType.DIFFERENT));
}

Reference: Spring Boot 2.6 + Swagger startup exception: because "this.condition" is null

Answer 2

Well, the answer mentioned by @Lyncean Patel is not 100% correct because there is no OR in fixing this. From this github issue discussion thread, the way to fix it to do both:

1. set spring.mvc.pathmatch.matching-strategy: ant_path_matcher in application.properties
2. add this bean

@Bean
public WebMvcEndpointHandlerMapping webEndpointServletHandlerMapping(WebEndpointsSupplier webEndpointsSupplier, ServletEndpointsSupplier servletEndpointsSupplier, ControllerEndpointsSupplier controllerEndpointsSupplier, EndpointMediaTypes endpointMediaTypes, CorsEndpointProperties corsProperties, WebEndpointProperties webEndpointProperties, Environment environment) {
        List<ExposableEndpoint<?>> allEndpoints = new ArrayList();
        Collection<ExposableWebEndpoint> webEndpoints = webEndpointsSupplier.getEndpoints();
        allEndpoints.addAll(webEndpoints);
        allEndpoints.addAll(servletEndpointsSupplier.getEndpoints());
        allEndpoints.addAll(controllerEndpointsSupplier.getEndpoints());
        String basePath = webEndpointProperties.getBasePath();
        EndpointMapping endpointMapping = new EndpointMapping(basePath);
        boolean shouldRegisterLinksMapping = this.shouldRegisterLinksMapping(webEndpointProperties, environment, basePath);
        return new WebMvcEndpointHandlerMapping(endpointMapping, webEndpoints, endpointMediaTypes, corsProperties.toCorsConfiguration(), new EndpointLinksResolver(allEndpoints, basePath), shouldRegisterLinksMapping, null);
    }


private boolean shouldRegisterLinksMapping(WebEndpointProperties webEndpointProperties, Environment environment, String basePath) {
        return webEndpointProperties.getDiscovery().isEnabled() && (StringUtils.hasText(basePath) || ManagementPortType.get(environment).equals(ManagementPortType.DIFFERENT));
    }

Answer 3

You're looking for itertools.repeat():

Make an iterator that returns object over and over again. Runs indefinitely unless the times argument is specified.

Note that the dictionaries returned by itertools.repeat() will share the same memory; changes to one dictionary will be shared across all of the elements of the list. That can lead to some pretty confusing behavior.

To avoid this, you can use map() with copy.copy() (if everything in the dictionary is immutable) or copy.deepcopy() to ensure that the memory for each dictionary is separate:

from itertools import repeat
from copy import copy

lst = [1, 2, 3, 4]
d = {"Hello": "World"}

list(zip(lst, map(copy, repeat(d))))

This outputs:

[
 (1, {'Hello': 'World'}), (2, {'Hello': 'World'}),
 (3, {'Hello': 'World'}), (4, {'Hello': 'World'})
]