Question

这是MRE：

public class LoginActivity extends AppCompatActivity {

    private EditText mPhoneNumber, mCode;
    private Button mSend;

    private PhoneAuthProvider.OnVerificationStateChangedCallbacks mCallbacks;

    String mVerificationId;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        FirebaseApp.initializeApp(this);

        userIsLoggedIn();

        mPhoneNumber = findViewById(R.id. phoneNumber);
        mCode = findViewById(R.id.code);

        mSend = findViewById(R.id.send);

        mSend.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (mVerificationId != null)
                    verifyPhoneNumberWithCode();
                else
                    startPhoneNumberVerification();
            }
        });

        mCallbacks = new PhoneAuthProvider.OnVerificationStateChangedCallbacks() {
            @Override
            public void onVerificationCompleted(PhoneAuthCredential phoneAuthCredential) {
                signInWithPhoneAuthCredential(phoneAuthCredential);
            }

            @Override
            public void onVerificationFailed(FirebaseException e) {}

            @Override
            public void onCodeSent(String verificationId, PhoneAuthProvider.ForceResendingToken forceResendingToken) {
                super.onCodeSent(verificationId, forceResendingToken);

                mVerificationId = verificationId;
                mSend.setText("Verify Code");

            }
        };
    }

    private void verifyPhoneNumberWithCode(){
        PhoneAuthCredential credential = PhoneAuthProvider.getCredential(mVerificationId, mCode.getText().toString());
        signInWithPhoneAuthCredential(credential);
    }

    private void signInWithPhoneAuthCredential(PhoneAuthCredential phoneAuthCredential) {
        FirebaseAuth.getInstance().signInWithCredential(phoneAuthCredential).addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
            @Override
            public void onComplete(@NonNull Task<AuthResult> task) {

            }if(task.isSuccesful()){    // **here is the PROBLEM**
                    final FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();

                    if (user != null){
                        final DatabaseReference mUserDB = FirebaseDatabase.getInstance().getReference().child("user").child(user.getUid());
                        mUserDB.addListenerForSingleValueEvent(new ValueEventListener() {
                            @Override
                            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                                if (!dataSnapshot.exists()){
                                    Map<String, Object> userMap = new HashMap<>();
                                    userMap.put("phone", user.getPhoneNumber());
                                    userMap.put("name", user.getPhoneNumber());
                                    mUserDB.updateChildren(userMap);
                                }
                            }

                            @Override
                            public void onCancelled(@NonNull DatabaseError databaseError) {}
                        });
                    }
                }
                    //userIsLoggedIn();

        });
    }

    private void userIsLoggedIn() {
        FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
        if (user != null){
            startActivity(new Intent(getApplicationContext(), MainPageActivity.class));
            finish();
            return;
        }
    }

    private void startPhoneNumberVerification() {
        PhoneAuthProvider.getInstance().verifyPhoneNumber(
                mPhoneNumber.getText().toString(),
                60,
                TimeUnit.SECONDS,
                this,
                mCallbacks);
    }
}

我想做的是遍历每个字典，并将每个值附加到数据框中的一列。

我现在正在做

data = [
    {'1':20},
    {'1':10},
    {'1':40},
    {'1':14},
    {'1':33}
]

输出：

import pandas as pd
lst = []
for item in data:
    lst.append(item['1'])

df = pd.DataFrame({"col1":lst})

是的，这是我想要的，但是列表中有超过100万个字典。这是最有效的方法吗？

编辑： col1 0 20 1 10 2 40 3 14 4 33 完全适用于上述情况，但是如果数据看起来像这样呢？

pd.DataFrame(data).rename(columns={'1':'col1'})

所以我会用：

data = [
    {'1':
     {'value':20}},
    {'1':
     {'value':10}},
    {'1':
      {'value':40}},
    {'1':
      {'value':14}},
    {'1':
      {'value':33}}]

有没有更有效的方法来查找包含字典的字典列表？

Answer 1

一个想法是将data传递给DataFrame辅助控制器，然后使用rename：

df = pd.DataFrame(data).rename(columns={'1':'col1'})
print (df)
   col1
0    20
1    10
2    40
3    14
4    33

如果有必要进行过滤，请使用列表理解并添加参数columns：

df = pd.DataFrame([x['1'] for x in data], columns=['col1'])
print (df)
   col1
0    20
1    10
2    40
3    14
4    33

编辑：对于新数据，请使用：

data = [
    {'1':
     {'value':20}},
    {'1':
     {'value':10}},
    {'1':
      {'value':40}},
    {'1':
      {'value':14}},
    {'1':
      {'value':33}}]

df = pd.DataFrame([x['1']['value'] for x in data], columns=['col1'])
print (df)
   col1
0    20
1    10
2    40
3    14
4    33

或者：

df = pd.DataFrame([x['1'] for x in data]).rename(columns={'value':'col1'})
print (df)
   col1
0    20
1    10
2    40
3    14
4    33

Answer 2

@jezrael的回答是正确的，但更具体地讲col：

df = pd.DataFrame(data)
print(df.add_prefix('col'))

输出：

遍历字典列表并将项追加到数据框中的列的有效方法

2 个答案: