Question: I am having the error :

> 
> "Could not resolve symbol itemActivity."
> 
> 
> 

This is in a method I want to use to open another activity. I have created the activity and i tried putting the name in the MainActivity. But its giving me error This is unusual as i have tried most of the solutions provide in previous question such as this. I have invalidate cache and restart. I have even rebuild the project but its still not working.

```
 package com.example.android.listofitems;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

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

}

public void openItemsList (View view) {
    Intent itemIntent = new Intent(this, itemActivity.class);
    startActivity(itemIntent);
}}

```

Answer: 
You could build a new index via

```
index = 100 * pd.RangeIndex(start=1, stop=7)

```

and use it to reindex your DataFrame and fill the created NaN values with forwardfill.

```
df = df.reindex(index).fillna(method='ffill')

```
Not sure whether that is any better than what you have at the moment but it leads to the desired output:

```
index_delta = df.index[-1] - df.index[-2]

max_index = 700

df2 = pd.DataFrame({'values': df.values[-1]}, index=range(df.index[-1], max_index + index_delta, index_delta))

print(pd.concat([df, df2]))

```

yields:

```
     values
100      10
200       9
300      15
400       7
400       7
500       7
600       7
700       7

```