How can i get all values of a second level key in a JSON?
I need to get all total values as like 409571117, 410559043, 411028977, 411287235
JSON:
{"country":"USA","timeline":
[{"total":409571117,"daily":757824,"totalPerHundred":121,"dailyPerMillion":2253,"date":"10/14/21"},
{"total":410559043,"daily":743873,"totalPerHundred":122,"dailyPerMillion":2212,"date":"10/15/21"},
{"total":411028977,"daily":737439,"totalPerHundred":122,"dailyPerMillion":2193,"date":"10/16/21"},
{"total":411287235,"daily":731383,"totalPerHundred":122,"dailyPerMillion":2175,"date":"10/17/21"}]}
I can able to get first level values but i don't know how to get second level.
final list = [
{'id': 1, 'name': 'flutter', 'title': 'dart'},
{'id': 35, 'name': 'flutter', 'title': 'dart'},
{'id': 93, 'name': 'flutter', 'title': 'dart'},
{'id': 82, 'name': 'flutter', 'title': 'dart'},
{'id': 28, 'name': 'flutter', 'title': 'dart'},
];
final idList = list.map((e) => e['id']).toList(); // [1, 35, 93, 82, 28]
python version of same question: Python: Getting all values of a specific key from json
UPDATE: You must declare the types in map. See below.
Have you tried subsetting on timeline after using jsonDecode?
For example, you format the data as json:
final newList = jsonEncode(
{ "country": "USA", "timeline":[
{ "total": 409571117, "daily": 757824, "totalPerHundred": 121, "dailyPerMillion": 2253, "date": "10/14/21" },
{"total": 410559043, ...
Then you decode the data into the list you want by first subsetting the timeline feature:
final extractedData = jsonDecode(newList) as Map<String, dynamic>;
final newIdList = extractedData['timeline'].map((e) => e["total"]).toList();
Related
Here I have a list of maps.
[
{
'name': 'name1',
'age': 30,
},
{
'name': 'name2',
'age': 20,
},
{
'name': 'name1',
'age': 15,
},
]
I need to access to 'name': 'name1' map from above list.
-- Access or extract maps --
i. e. List[0] and(or) List[2]
How do I do this kind of thing???
You can loop through the list and find items, .where will return list of found item. .firstWhere for single item return.
final data = [
{
'name': 'name1',
'age': 30,
},
{
'name': 'name2',
'age': 20,
},
{
'name': 'name1',
'age': 15,
},
];
final findValue = "name1";
final result = data.where((element) => element["name"] == findValue);
print(result); //({name: name1, age: 30}, {name: name1, age: 15})
result.forEach((element) {
print("${element["name"]} ${element["age"]}");
});
More about List
I have a List<Map<String, String>> like below
[
{ 'name': 'John', 'id': 'aa' },
{ 'name': 'Jane', 'id': 'bb' },
{ 'name': 'Lisa', 'id': 'cc' },
]
And, the ID list **List** as ['bb', 'aa']. By using the ID list, I want to return a new list ['Jane', 'John'] as **List _selectedList**.
I have tried to do it with the .**indexWhere**, however, I am stuck on the List where it has more than one value.
How can I return the List only with the name-value when there is more than one value to look for?
void main() {
var a = [
{ 'name': 'John', 'id': 'aa' },
{ 'name': 'Jane', 'id': 'bb' },
{ 'name': 'Lisa', 'id': 'cc' },
];
var b = ['bb', 'aa'];
var c = a.where((m) => b.contains(m['id'])).map((m) => m['name']);
print(c);
}
Result
(John, Jane)
Use a set to filter out the IDs efficiently.
var ids = ["aa", "cc"];
var idSet = Set<String>.from(ids);
var json = [
{ 'name': 'John', 'id': 'aa' },
{ 'name': 'Jane', 'id': 'bb' },
{ 'name': 'Lisa', 'id': 'cc' },
];
var _selectedList = json.where((data) => idSet.contains(data["id"]))
.map((data) => data["name"]).toList();
print(_selectedList);
Here, .where filters out the data where the ID matches one in the input list "IDs". Sets make the process efficient. Then, the resultant objects are passed to .map where the "name" field is extracted. Finally, the whole thing is converted into a list thus returning the list of names.
Output of the above code:
[John, Lisa]
I have a List that contains nested objects.
List _haha = [
{id: 'aaa'},
{id: 'bbb'},
{id: 'ccc'},
{id: 'ddd'},
];
I want to delete 'aaa' inside the _haha. Currently, I did
int _indexVal = _haha.indexWhere((e) => e['id'] == 'aaa');
And, use this int value to remove the item inside the list. Is there any way that I can use .removeAt with one single line?
Oneliner with .removeAt():
void main() {
List<Map<String, String>> haha = [
{'id': 'aaa'},
{'id': 'bbb'},
{'id': 'ccc'},
{'id': 'ddd'},
];
haha.removeAt(haha.indexWhere((item) => item['id'] == 'aaa'));
}
But, you may be more interested in using the .removeWhere() method.
void main() {
List<Map<String, String>> haha = [
{'id': 'aaa'},
{'id': 'bbb'},
{'id': 'ccc'},
{'id': 'ddd'},
];
haha.removeWhere((item) => item['id'] == 'aaa');
}
I have two topics:
// photos
{'id': 1, 'user_id': 1, 'url': 'url#1'},
{'id': 2, 'user_id': 2, 'url': 'url#2'},
{'id': 3, 'user_id': 2, 'url': 'url#3'}
// users
{'id': 1, 'name': 'user#1'},
{'id': 1, 'name': 'user#1'},
{'id': 1, 'name': 'user#1'}
I create map photo by user
KStream<Integer, Photo> photo_by_user = ...
photo_by_user.to("photo_by_user")
Then, I try to join two tables:
KTable<Integer, User> users_table = builder.table("users");
KTable<Integer, Photo> photo_by_user_table = builder.table("photo_by_user");
KStream<Integer, Result> results = users_table.join(photo_by_user_table, (a, b) -> Result.from(a, b)).toStream();
results.to("results");
result like
{'photo_id': 1, 'user': 1, 'url': 'url#1', 'name': 'user#1'}
{'photo_id': 2, 'user': 2, 'url': 'url#2', 'name': 'user#2'}
{'photo_id': 3, 'user': 3, 'url': 'url#3', 'name': 'user#3'}
{'photo_id': 1, 'user': 1, 'url': 'url#1', 'name': 'user#1'}
{'photo_id': 2, 'user': 2, 'url': 'url#2', 'name': 'user#2'}
{'photo_id': 3, 'user': 3, 'url': 'url#3', 'name': 'user#3'}
I see that results are duplicated. Why, and how to avoid it?
You might hit a known bug. On "flush" KTable-KTable join might produce some duplicates. Note, that those duplicates are strictly speaking not incorrect, because the result is an update-stream and updating "A" to "A" does not change the result. It's of course undesired to get those duplicates. Try to disable caching -- without caching, the "flush issues" should not occur.
I want to use d3js to visualize the connections between the users of my Django website.
I am reusing the code for the force directed graph example wich requires that each node has two attributes (ID and Name). I have created a node for each user in user_profiles_table and added an edge between already created nodes based on each row in connections_table. It does not work; networkx creates new nodes when I start working with the connection_table.
nodeindex=0
for user_profile in UserProfile.objects.all():
sourcetostring=user_profile.full_name3()
G.add_node(nodeindex, name=sourcetostring)
nodeindex = nodeindex +1
for user_connection in Connection.objects.all():
target_tostring=user_connection.target()
source_tostring=user_connection.source()
G.add_edge(sourcetostring, target_tostring, value=1)
data = json_graph.node_link_data(G)
result:
{'directed': False,
'graph': [],
'links': [{'source': 6, 'target': 7, 'value': 1},
{'source': 7, 'target': 8, 'value': 1},
{'source': 7, 'target': 9, 'value': 1},
{'source': 7, 'target': 10, 'value': 1},
{'source': 7, 'target': 7, 'value': 1}],
'multigraph': False,
'nodes': [{'id': 0, 'name': u'raymondkalonji'},
{'id': 1, 'name': u'raykaeng'},
{'id': 2, 'name': u'raymondkalonji2'},
{'id': 3, 'name': u'tester1cet'},
{'id': 4, 'name': u'tester2cet'},
{'id': 5, 'name': u'tester3cet'},
{'id': u'tester2cet'},
{'id': u'tester3cet'},
{'id': u'tester1cet'},
{'id': u'raykaeng'},
{'id': u'raymondkalonji2'}]}
How can I eliminate the repeated nodes?
You probably get repeated nodes because your user_connection.target() and user_connection.source() functions return the node name, not its id. When you call add_edge, if the endpoints do not exist in the graph, they are created, which explain why you get duplicates.
The following code should work.
for user_profile in UserProfile.objects.all():
source = user_profile.full_name3()
G.add_node(source, name=source)
for user_connection in Connection.objects.all():
target = user_connection.target()
source = user_connection.source()
G.add_edge(source, target, value=1)
data = json_graph.node_link_data(G)
Also note that you should dump the data object to json if you want a properly formatted json string. You can do that as follows.
import json
json.dumps(data) # get the string representation
json.dump(data, 'somefile.json') # write to file