# Week 2 Lab: Exploratory Data Analysis - Data Visualization and Summary Statistics

Dear Mentor,

Could you please guide me how to calculate the scale number of the colorbar when density is true?

If Density = False, range is from 0 to 20000+

hist = ax.hist2d(longitude, latitude, bins=50, density=False)

If Density = True, range is from 0 to 600+

hist = ax.hist2d(longitude, latitude, bins=50, density=True)

Note:
Length of longitude = Length of latitude = 575485
According to matplotlib,
https://matplotlib.org/stable/api/_as_gen/matplotlib.axes.Axes.hist.html#matplotlib.axes.Axes.hist

density = counts / (sum(counts) * np.diff(bins))

I assume that
sum(counts) = 575485
count = 20000 (estimated from the first figure)
bin width = 0.05 / 6 = 0.008 (estimated)
density = 20000 / (575485 * 0.008) = 4.344 (This is not 600 from the second figure)

and also

I thought that the probability density must be within 0 to 1 but it shows that a range from 0 to 600+

Please correct me for any mistakes.

Thank you.

Where did your equation for density come from?

Dear Mr Tom Mosher,

The equation for density is taken from matplotlib documentation.

Parameter:
→ density : bool, default: False

https://matplotlib.org/stable/api/_as_gen/matplotlib.axes.Axes.hist.html#matplotlib.axes.Axes.hist

Thank you.

You mentioned a specific lab in the thread title. I went to that lab to see about getting more information on this issue.

The lab I see by that name in the course does not generate the plot you posted.

So I am confused.

Dear Mr Tom Mosher,

Please refer to this link to access the lab, and proceed to the Section “4. Check the Locations of Rides”

Thank you.