I'm calculating 2 moving averages from a stock price and finding if they crossed over. When they crossover, I want to show in the graph a marker on top of it.

To find the crossovers, I'm using this code: 

```
idxs = np.argwhere(np.diff(df_status)).flatten()

```

where df\_status is a list with -1, 0 and 1 from the two moving averages. The idxs gives me the index position from df\_status where the crossover happened.

The problem is when the cross is between 2 dates, as seen in the picture below:
[![crossover between SMA 10 and 100. Blue line is stock price](https://i.stack.imgur.com/jHqHd.jpg)](https://i.stack.imgur.com/jHqHd.jpg)

How can I move the marker to be centered on the crossover than in the date that it was detected?

Code to reproduce:

```py
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.image as mpimg

data = [
    ["2019-12-16", 4.39, 4.02, 5.11],
    ["2019-12-17", 4.42, 4.08, 5.09],
    ["2019-12-18", 4.2, 4.11, 5.06],
    ["2019-12-19", 4.57, 4.18, 5.04],
    ["2019-12-20", 4.85, 4.27, 5.03],
    ["2019-12-23", 4.95, 4.36, 5.01],
    ["2019-12-26", 5.8, 4.54, 5.01],
    ["2019-12-27", 6.0, 4.74, 5.01],
    ["2019-12-30", 5.9, 4.92, 5.0],
    ["2020-01-02", 6.02, 5.11, 5.00]
]
columns = ["day", "price", "SMA_10", "SMA_100"]

df = pd.DataFrame(data, columns=columns)
df['status_SMA_10_SMA_100'] = np.sign(df['SMA_10'] - df['SMA_100'])
idxs = np.argwhere(np.diff(df['status_SMA_10_SMA_100'])).flatten() # get crossovers

fig = plt.figure(figsize=[15, 8])
ax = fig.gca()
plt.grid(True)
plt.plot(df['day'], df['price'])
plt.plot(df['day'], df['SMA_10'])
plt.plot(df['day'], df['SMA_100'])
for marker in idxs:
    ax.plot(df['day'][marker], df['SMA_100'][marker], marker='o', markersize=35, alpha=.5)
    ax.plot(df['day'][marker + 1], df['SMA_100'][marker], marker='o', markersize=35, alpha=.5)
plt.show()

```

In this code, the crossover is at index 8, but the crossover happen in the graph between indexes 8 and 9. How can I position the marker between the two X ticks?