How can I draw a Line in the Price Bar Pane/Window from an Indicator that is in its own Pane/Window. Think drawing a Line on the Price Bars from a MACD Indicator.
if this is the Line struct:
line.new(x1, y1, x2, y2, xloc, extend, color, style, width) → series line
then how do I do it?
What am I missing?
Related
In this diagram I have distributed the ticks and applied a tick:
ax.set_xticks(np.arange(0, 800, 1))
ax.grid()
How can I label on the x-axis only the numbers present in the legend?
Regards,
Karl
Try this to keep all grid points, but only label the points of interest.
original_labels = [str(label) for label in ax.get_xticks()]
labels_of_interest = [str(i) for i in np.arange(235,295,5)]
new_labels = [label if label in labels_of_interest else "" for label in original_labels]
ax.set_xticklabels(new_labels)
Edit:
an optional parameter to ax.set_xticklabels is rotation. If you find your labels are still overlapping, try rotating them:
ax.set_xticklabels(new_labels, rotation=45) #rotate labels 45 degrees
# use a gray background
ax = plt.axes(facecolor='#E6E6E6')
ax.set_axisbelow(True)
# draw solid white grid lines
plt.grid(color='w', linestyle='solid')
# hide axis spines
for spine in ax.spines.values():
spine.set_visible(True)
# hide top and right ticks
ax.xaxis.tick_bottom()
ax.yaxis.tick_left()
# lighten ticks and labels
ax.tick_params(colors='gray', direction='out')
for tick in ax.get_xticklabels():
tick.set_color('gray')
for tick in ax.get_yticklabels():
tick.set_color('gray')
# control face and edge color of histogram
ax.hist(x, edgecolor='#E6E6E6', color='#EE6666');
Output:
The codes above generate the pic attached. How can I get rid of the black frame circulating the axes?
The "black frame" surrounding your image is part of the figure container. The short answer is, change the facecolor of the figure. (i.e. add, fig = plt.figure(facecolor='white') above your first line.)
# THIS LINE CONTROLS THE FIGURE FACECOLOR. YOU CAN USE HEX COLOR RGB OR JUST SPECIFY A COLOR
fig = plt.figure(facecolor='white')
# use a gray background
ax = plt.axes(facecolor='#E6E6E6')
ax.set_axisbelow(True)
# draw solid white grid lines
plt.grid(color='w', linestyle='solid')
# hide axis spines
for spine in ax.spines.values():
spine.set_visible(True)
# hide top and right ticks
ax.xaxis.tick_bottom()
ax.yaxis.tick_left()
# lighten ticks and labels
ax.tick_params(colors='gray', direction='out')
for tick in ax.get_xticklabels():
tick.set_color('gray')
for tick in ax.get_yticklabels():
tick.set_color('gray')
# control face and edge color of histogram
ax.hist(x, edgecolor='#E6E6E6', color='#EE6666');
Similar to in this StackOverflow post, I understand that it is possible to extract the pixel co-ordinates from points plotted in a pyplot figure.
How to get pixel coordinates for Matplotlib-generated scatterplot?
However, what if we plotted a line between each of those points and wanted to get the location of all the pixels of not just those plotted dots, but all pixels that make up the line.
Is this something that is possible with matplotlib?
A line isn't made up of pixels. The pixels in its trajectory are modified taking line width and antialiasing into account. Drawing a line with default settings and zooming in on the image looks like the image below. Very few pixels get the full 100% of the given color. Lots of pixels are changed.
Depending on your final goal, you could calculate pixel coordinates using the method described in the post you linked (note that the pixels on a saved image can deviate a bit from the pixels on-screen). And then use e.g. Bresenham's line algorithm to find the coordinates of points in-between. Note that a naive Bresenham's algorithm would draw a 45 degree line much thinner looking than a horizontal line. On a modern screen a one-pixel wide line would be almost invisible.
Here is a possible Bresenham-like interpretation of the linked code:
import numpy as np
import matplotlib.pyplot as plt
def points_in_line(x0, y0, x1, y1):
dx = np.round(np.abs(x1 - x0))
dy = np.round(np.abs(y1 - y0))
steps = int(np.round(max(dx, dy))) + 1
return np.vstack([np.linspace(x0, x1, steps), np.linspace(y0, y1, steps)]).T
fig, ax = plt.subplots()
points, = ax.plot([0, 1, 2, 4, 5, 6, 9], [0, 5, 3, 2, 2, 9, 8], 'b-')
ax.axis([-1, 10, -1, 10])
# Get the x and y data and transform them into pixel coordinates
x, y = points.get_data()
xy_pixels = ax.transData.transform(np.vstack([x, y]).T)
x_pix, y_pix = xy_pixels.T
# find all points in each line
all_pix = [points_in_line(x0, y0, x1, y1) for x0, y0, x1, y1 in zip(x_pix[:-1], y_pix[:-1], x_pix[1:], y_pix[1:])]
all_x_pix, all_y_pix = np.concatenate(all_pix).T
# In matplotlib, 0,0 is the lower left corner, whereas it's usually the upper
# left for most image software, so we'll flip the y-coords...
width, height = fig.canvas.get_width_height()
all_y_pix = height - all_y_pix
print('Coordinates of the lines in pixel coordinates...')
for xp, yp in zip(all_x_pix, all_y_pix):
print(f'{x:0.2f}\t{y:0.2f}')
# save the figure with its current DPI
fig.savefig('test.png', dpi=fig.dpi)
How to properly give Annotations to Pandas Bar Charts?
I'm following Bar Chart Annotations with Pandas and MPL, but somehow I can't make it into my own code -- this is as far as I can go. What's wrong?
I've also found the following code from here:
def autolabel(rects):
# attach some text labels
for rect in rects:
height = rect.get_height()
ax.text(rect.get_x() + rect.get_width()/2., 1.05*height,
'%d' % int(height),
ha='center', va='bottom')
autolabel(rects1)
autolabel(rects2)
But I don't how to apply that to my code either. Please help.
UPDATE:
Thank you #CT Zhu, for the answer. However, in your horizontal bars, you are still placing the text on top of bars, but I need the text show up within or along them, like this from my referenced article,
where s/he says,
"I am very parital to horizontal bar charts, as I really think they are easier to read, however, I understand that a lot of people would rather see this chart implemented in a regular bar chart. So, here is the code to do that; you will notice that a few things have changed in order to create the annotation"*
It appears your autolabel function is expecting a list of patches, sssuming your plot only those bars as its patches, we could do:
df = pd.DataFrame({'score':np.random.randn(6),
'person':[x*3 for x in list('ABCDEF')]})
def autolabel(rects):
x_pos = [rect.get_x() + rect.get_width()/2. for rect in rects]
y_pos = [rect.get_y() + 1.05*rect.get_height() for rect in rects]
#if height constant: hbars, vbars otherwise
if (np.diff([plt.getp(item, 'width') for item in rects])==0).all():
scores = [plt.getp(item, 'height') for item in rects]
else:
scores = [plt.getp(item, 'width') for item in rects]
# attach some text labels
for rect, x, y, s in zip(rects, x_pos, y_pos, scores):
ax.text(x,
y,
'%s'%s,
ha='center', va='bottom')
ax = df.set_index(['person']).plot(kind='barh', figsize=(10,7),
color=['dodgerblue', 'slategray'], fontsize=13)
ax.set_alpha(0.8)
ax.set_title("BarH")#,fontsize=18)
autolabel(ax.patches)
ax = df.set_index(['person']).plot(kind='bar', figsize=(10,7),
color=['dodgerblue', 'slategray'], fontsize=13)
ax.set_alpha(0.8)
ax.set_title("Bar")#,fontsize=18)
autolabel(ax.patches)
I do not quite understand why I am unable to create horizontal and vertical lines at specified limits. I would like to bound the data by this box. However, the sides do not seem to comply with my instructions. Why is this?
# CREATING A BOUNDING BOX
# BOTTOM HORIZONTAL
plt.axhline(y=.4, xmin=0.25, xmax=0.402, linewidth=2, color = 'k')
# RIGHT VERTICAL
plt.axvline(x=0.402, ymin=0.4, ymax = 0.615, linewidth=2, color='k')
# LEFT VERTICAL
plt.axvline(x=0.1, ymin=0.58, ymax = 0.79, linewidth=2, color='k')
plt.show()
The pyplot functions you are calling, axhline() and axvline() draw lines that span a portion of the axis range, regardless of coordinates. The parameters xmin or ymin use value 0.0 as the minimum of the axis and 1.0 as the maximum of the axis.
Instead, use plt.plot((x1, x2), (y1, y2), 'k-') to draw a line from the point (x1, y1) to the point (x2, y2) in color k. See pyplot.plot.
This may be a common problem for new users of Matplotlib to draw vertical and horizontal lines. In order to understand this problem, you should be aware that different coordinate systems exist in Matplotlib.
The method axhline and axvline are used to draw lines at the axes coordinate. In this coordinate system, coordinate for the bottom left point is (0,0), while the coordinate for the top right point is (1,1), regardless of the data range of your plot. Both the parameter xmin and xmax are in the range [0,1].
On the other hand, method hlines and vlines are used to draw lines at the data coordinate. The range for xmin and xmax are the in the range of data limit of x axis.
Let's take a concrete example,
import matplotlib.pyplot as plt
import numpy as np
x = np.linspace(0, 5, 100)
y = np.sin(x)
fig, ax = plt.subplots()
ax.plot(x, y)
ax.axhline(y=0.5, xmin=0.0, xmax=1.0, color='r')
ax.hlines(y=0.6, xmin=0.0, xmax=1.0, color='b')
plt.show()
It will produce the following plot:
The value for xmin and xmax are the same for the axhline and hlines method. But the length of produced line is different.
If you want to add a bounding box, use a rectangle:
ax = plt.gca()
r = matplotlib.patches.Rectangle((.5, .5), .25, .1, fill=False)
ax.add_artist(r)
Rectangle doc