The objective is to modify the xticklabel upon plotting pcolormesh and scatter.
However, I am having difficulties accessing the existing xtick labels.
Simply
ax = plt.axes()
labels_x = [item.get_text() for item in ax.get_xticklabels()]
which produced:
['', '', '', '', '', '']
or
fig.canvas.draw()
xticks = ax.get_xticklabels()
which produced:
['', '', '', '', '', '']
does not return the corresponding label.
May I know how to properly access axis tick labels for a plt cases.
For readability, I split the code into two section.
- The first section to generate the data used for plotting
- Second section deal the plotting
Section 1: Generate data used for plotting
import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
import math
np.random.seed(0)
increment=120
max_val=172800
aran=np.arange(0,max_val,increment).astype(int)
arr=np.concatenate((aran.reshape(-1,1), np.random.random((aran.shape[0],4))), axis=1)
df=pd.DataFrame(arr,columns=[('lapse',''),('a','i'),('a','j'),('b','k'),('c','')])
ridx=df.index[df[('lapse','')] == 3600].tolist()[0] 1 # minus 1 so to allow 3600 start at new row
df[('event','')]=0
df.loc[[1,2,3,10,20,30],[('event','')]]=1
arr=df[[('a','i'),('event','')]].to_numpy()
col_len=ridx
v=arr[:,0].view()
nrow_size=math.ceil(v.shape[0]/col_len)
X=np.pad(arr[:,0].astype(float), (0, nrow_size*col_len - arr[:,0].size),
mode='constant', constant_values=np.nan).reshape(nrow_size,col_len)
mask_append_val=0 # This value must equal to 1 for masking
arrshape=np.pad(arr[:,1].astype(float), (0, nrow_size*col_len - arr[:,1].size),
mode='constant', constant_values=mask_append_val).reshape(nrow_size,col_len)
Section 2 Plotting
fig = plt.figure(figsize=(8,6))
plt.pcolormesh(X,cmap="plasma")
x,y = X.shape
xs,ys = np.ogrid[:x,:y]
# the non-zero coordinates
u = np.argwhere(arrshape)
plt.scatter(ys[:,u[:,1]].ravel() .5,xs[u[:,0]].ravel() 0.5,marker='*', color='r', s=55)
plt.gca().invert_yaxis()
xlabels_to_use_this=df.loc[:30,[('lapse','')]].values.tolist()
# ax = plt.axes()
# labels_x = [item.get_text() for item in ax.get_xticklabels()]
# labels_y = [item.get_text() for item in ax.get_yticklabels()]
plt.xlabel('X-axis')
plt.ylabel('Y-axis')
plt.title("Plot 2D array")
plt.colorbar()
plt.tight_layout()
plt.show()
Expected output
CodePudding user response：
I end up using Seaborn to address this issue.
Specifically, the following lines able to easily tweak the xticklabel
fig.canvas.draw()
new_ticks = [i.get_text() for i in g.get_xticklabels()]
i=[int(idx) for idx in new_ticks]
newlabel=xlabels_to_use_this[i]
newlabel=[np.array2string(x, precision=0) for x in newlabel]
The full code for plotting is as below
import seaborn as sns
fig, ax = plt.subplots()
sns.heatmap(X,ax=ax)
x,y = X.shape
xs,ys = np.ogrid[:x,:y]
# the non-zero coordinates
u = np.argwhere(arrshape)
g=sns.scatterplot(ys[:,u[:,1]].ravel() .5,xs[u[:,0]].ravel() 0.5,marker='*', color='r', s=55)
fig.canvas.draw()
new_ticks = [i.get_text() for i in g.get_xticklabels()]
i=[int(idx) for idx in new_ticks]
newlabel=xlabels_to_use_this[i]
newlabel=[np.array2string(x, precision=0) for x in newlabel]
ax.set_xticklabels(newlabel)
ax.set_xticklabels(ax.get_xticklabels(),rotation = 90)
for ind, label in enumerate(g.get_xticklabels()):
if ind % 2 == 0: # every 10th label is kept
label.set_visible(True)
else:
label.set_visible(False)
for ind, label in enumerate(g.get_yticklabels()):
if ind % 4 == 0: # every 10th label is kept
label.set_visible(True)
else:
label.set_visible(False)
plt.xlabel('Elapsed (s)')
plt.ylabel('Hour (h)')
plt.title("Rastar Plot")
plt.tight_layout()
plt.show()
CodePudding user response：
This is how the plot could be generated using matplotlib's pcolormesh and scatter:
import matplotlib.pyplot as plt
from matplotlib.ticker import MultipleLocator
import pandas as pd
import numpy as np
np.random.seed(0)
increment = 120
max_val = 172800
aran = np.arange(0, max_val, increment).astype(int)
arr_df = np.concatenate((aran.reshape(-1, 1), np.random.random((aran.shape[0], 4))), axis=1)
df = pd.DataFrame(arr_df, columns=[('lapse', ''), ('a', 'i'), ('a', 'j'), ('b', 'k'), ('c', '')])
df[('event', '')] = 0
df.loc[[1, 2, 3, 10, 20, 30], [('event', '')]] = 1
col_len_lapse = 3600
col_len = df[df[('lapse', '')] == col_len_lapse].index[0]
nrow_size = int(np.ceil(v.shape[0] / col_len))
a_i_values = df[('a', 'i')].values
a_i_values_meshed = np.pad(a_i_values.astype(float), (0, nrow_size * col_len - len(a_i_values)),
mode='constant', constant_values=np.nan).reshape(nrow_size, col_len)
fig, ax = plt.subplots(figsize=(8, 6))
# the x_values indicate the mesh borders, subtract one half so the ticks can be at the centers
x_values = df[('lapse', '')][:col_len 1].values - increment / 2
# divide lapses for y by col_len_lapse to get hours
y_values = df[('lapse', '')][::col_len].values / col_len_lapse - 0.5
y_values = np.append(y_values, 2 * y_values[-1] - y_values[-2]) # add the bottommost border (linear extension)
mesh = ax.pcolormesh(x_values, y_values, a_i_values_meshed, cmap="plasma")
event_lapses = df[('lapse', '')][df[('event', '')] == 1]
ax.scatter(event_lapses % col_len_lapse,
np.floor(event_lapses / col_len_lapse),
marker='*', color='red', edgecolor='white', s=55)
ax.xaxis.set_major_locator(MultipleLocator(increment * 5))
ax.yaxis.set_major_locator(MultipleLocator(5))
ax.invert_yaxis()
ax.set_xlabel('X-axis (s)')
ax.set_ylabel('Y-axis (hours)')
ax.set_title("Plot 2D array")
plt.colorbar(mesh)
plt.tight_layout() # fit the labels nicely into the plot
plt.show()
With Seaborn things can be simplified, adding new columns for hours and seconds, and using pandas' pivot (which automatically fills unavailable data with NaNs). Adding xtick_labels=5 sets the labels every 5 positions. (The star for lapse=3600 is at 1 hour, 0 seconds).
import matplotlib.pyplot as plt
import seaborn as sns
import pandas as pd
import numpy as np
# df created as before
df['hours'] = (df[('lapse', '')].astype(int) // 3600)
df['seconds'] = (df[('lapse', '')].astype(int) % 3600)
df_heatmap = df.pivot(index='hours', columns='seconds', values=('a', 'i'))
df_heatmap_markers = df.pivot(index='hours', columns='seconds', values=('event', '')).replace(
{0: '', 1: '★', np.nan: ''})
fig, ax = plt.subplots(figsize=(8, 6))
sns.heatmap(df_heatmap, xticklabels=5, yticklabels=5,
annot=df_heatmap_markers, fmt='s', annot_kws={'color': 'lime'}, ax=ax)
ax.tick_params(rotation=0)
plt.tight_layout()
plt.show()
PS: Instead of a 'seconds' column, a 'minutes' column also might be interesting.
CodePudding user response：
The docs mention the following:
Notes The tick label strings are not populated until a draw method has been called.
So, place ax.get_xticklabels() after plt.show(). Does that work? (also see 32700935)