add m4 reflection

docs/reflection-milestone4.md

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+# Reflection - milestone 4
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+Our group has implemented various features on our dashboard so far, including a map visualization, three summary statistic boxes and two bar plots showing the temperature and precipitation of different cities in the United States. We have received a lot of valuable feedback from our peer classmates, including saying our app is organized and easy to use without reading the documentation. In the previous milestone, we had doubts about using two tabs on our dashboard, but we are glad and appreciate that the peer users support our decision and think it is reasonable and more organized to split the dashboard into two tabs for different topics, where one is showing the trends in temperature and precipitation of a city and the other one is for ranking of cities in a state.
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+The peer users also provided a lot of other constructive feedback and we have picked several of them to improve our dashboard. Some of them include tidying the city names and having bigger fonts for some plots. We agree that these improvements can improve the visual experience, so we have made the appropriate changes. In response to the suggestions provided by the teaching assistant, we also made changes to the labels on the y-axis of our bar plots so that they are proportional to the number of bars displayed. Another constructive feedback from the peers was to add a widget so users could change between Imperial and Metrics systems. This improvement really makes sense because not all users are from the United States, so they might not be familiar with the Fahrenheit scale, which is the unit of the dataset. Another suggestion we received was to adjust the color scale on the map, as the warm colors we initially used could give the incorrect impression that temperatures in different cities across the United States were high. We agreed with this feedback and modified the color scale to use dull colors for colder temperatures and bright colors for warmer temperatures.
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+Overall, we have implemented all of the planned improvements and are satisfied with the current version of our dashboard. It might be better if we could add more plots or reactive elements to each tab in the future version, as we will have more time and might have more contributions from other outside contributors.