How to Correctly Order Y-Axis Values When Plotting String-Based Data in Matplotlib?

Matplotlib Y Axis Values Incorrectly Ordered

In Matplotlib, incorrect ordering of y-axis values is prevalent when dealing with string-based data. This issue arises specifically when plotting data that has been mistakenly represented as strings rather than numerical values.

For instance, consider the following code:

<code class="python">Solar = [line[1] for line in I020]</code>

In this example, the Solar list contains string values instead of numerical values. As a result, Matplotlib interprets these strings as categorical variables, leading to incorrect ordering of the y-axis labels.

To rectify this issue, it's essential to convert the string data to numerical values. This can be accomplished with a simple type cast:

<code class="python">Solar = [float(line[1]) for line in I020]</code>

By converting the Solar list elements to floats, we ensure that Matplotlib interprets them as numerical values, which will result in the correct ordering of the y-axis labels.

Additionally, to enhance the visual presentation of time-based data, it's recommended to utilize Matplotlib's auto formatting feature for the x-axis:

<code class="python">plt.gcf().autofmt_xdate()</code>

This function automatically adjusts the x-axis label rotation and alignment, improving the readability and aesthetics of the graph.

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