Various colorbars with Matplotlib

In the case of a two-dimensional plot, the types of data that can be expressed are up to three types using x-axis, y-axis and color. Following the MATLAB edition (https://qiita.com/Yuricst/items/1594cacb930bd4fa6d63), a memo about adding a colorbar in plot with Matplotlib in Python. (Even if it is not the optimal solution, it seems that this method will be enough for the time being. It will be updated from time to time.)

For scatter plots ( plt.scatter)

In the case of scatter, it is fairly simple, specify the array you want to use as a color parameter when using `scatter ()` with `c```, and specify the color map cmap``` Just specify with. Note that the `` fig.colorbar ()` `` used to add the colorbar requires a mappable object, so the scatter itself must be assigned as an object (im0 in the example below). .. When using subplot, if the color parameters are the same, there is no problem even if you do not assign all subplots as objects.

# assign color array
cc = transfer_df['Jacobi_LPO']

plt.rcParams["font.size"] = 16
fig, axs = plt.subplots(1, 3, figsize=(15, 6))
im0 = axs[0].scatter(transfer_df['loi_cost']*1000, transfer_df['incl'], c=cc, cmap='plasma', s=15, marker='x')
axs[0].set_xlabel('LOI cost [m/sec]')
axs[0].set_ylabel('Inclination [deg]')
axs[0].grid(True)

axs[1].scatter(transfer_df['loi_cost']*1000, transfer_df['raan'], c=cc, cmap='plasma', s=15, marker='x')
axs[1].set_xlabel('LOI cost [m/sec]')
axs[1].set_ylabel('RAAN [deg]')
axs[1].grid(True)

axs[2].scatter(transfer_df['loi_cost']*1000, -transfer_df['tof_EM_SOI']*Tstar_EM/(60*60*24), c=cc, cmap='plasma', s=15, marker='x')
axs[2].set_xlabel('LOI cost [m/sec]')
axs[2].set_ylabel('Tof til lunar SOI [days]')
axs[2].grid(True)


fig.colorbar(im0, label='LPO Jacobi')
plt.suptitle(f'Moon SOI leg, beta = {transfer_df.iloc[0,:]['beta0']}')
plt.tight_layout(rect=[0, 0.03, 1, 0.95])
plt.show()

For trajectories (`` `plt.plot```)

For plot, the process gets a little complicated. Roughly speaking --Save the data you want to plot in `points``` --Assign points``` and color bars in LineCollection --Added LineCollection to `` line``` It feels like (I wonder?).

# plot of the transfer (xy-plot)
fig, axs = plt.subplots(1, 1, figsize=(12,10))
plt.rcParams["font.size"] = 20

for j in tqdm( range(len(df_peritarg)) ):  
    # generate segments
    points = np.array([proptry["x_arr"] *Lstar , proptry["y_arr"] *Lstar]).T.reshape(-1, 1, 2)
    segments =np.concatenate([points[:-1], points[1:]], axis=1)
    
    loi_color = df_peritarg.iloc[j,:]["time2perilune"]*Tstar/86400 * np.ones(( len(proptry["x_arr"]) ,))
    
    # create color bar
    norm = plt.Normalize(min( df_peritarg["time2perilune"] )*Tstar/86400, max( df_peritarg["time2perilune"])*Tstar/86400)
    lc = LineCollection(segments, cmap='Reds', norm=norm)
    # Set the values used for colormapping
    lc.set_array( loi_color )
    lc.set_linewidth(0.8)
    line = axs.add_collection(lc)

# display colorbar
fig.colorbar(line, ax=axs, label="Transfer time [days]")

axs.grid()
axs.set_title(f'Targeting from {familydf.iloc[0,:]["family"]}')
axs.set_xlabel('x [km]')
axs.set_ylabel('y [km]')
axs.set_xlim(300000, 500000)
axs.set_ylim(-60000, 60000)
axs.set_aspect('equal')