[Python] How to append once instead of every loop [closed]

sorry for the whole code

I'm unsure how to simplify unfortunately

Context


Pose Keypoint extraction of picture/every frame in video

keypoint coordinates & calculated angles export to .csv for later analysis

import csv
import pandas as pd
from ultralytics import YOLO
from pathlib import Path
import numpy as np

model = YOLO("yolo11n-pose.pt")
results = model.track(source='file.png', save=False)

def calculate_angle(p1, p2, p3):
# p1, p2, p3 are the points in format [x, y]
# Calculate the vectors
v1 = np.array(p1) - np.array(p2)
v2 = np.array(p3) - np.array(p2)

# Calculate the angle in radians
angle_rad = np.arccos(np.dot(v1, v2) / (np.linalg.norm(v1) * np.linalg.norm(v2)))

# Convert to degrees
angle_deg = np.degrees(angle_rad)

return angle_deg


ja_list = [[9,7,5], [10,8,6], [7,5,11], [8,6,12], [5,11,13], [6,12,14], [11,13,15], [12,14,16]]

# Initialize an empty list to store data
data = []

for frame_id, (frame_results) in enumerate(results):
for person_id, person in enumerate(frame_results.keypoints):
xy = person.xyn.numpy() # keypoints coordinates
conf = person.conf.numpy() # confidence scores of keypoints
for kp_id, (xy, kp_conf) in enumerate(zip(xy, conf)):
xy_str = ', '.join(map(str, xy)) # Convert the array to a comma-separated string

data.append({"frame_id": frame_id, "person_id": person_id, "xy": xy_str})

for ja in ja_list:
angle = calculate_angle(xy[ja[0]],xy[ja[1]],xy[ja[2]])
str_angle = angle

data.append({"angles": str_angle})

df = pd.DataFrame(data)
df.to_csv('file.csv', escapechar=' ', quoting=csv.QUOTE_NONE, index=False)

Current Output


frame_id,person_id,nose , left eye , right eye , left ear , right ear , left shoulder , right shoulder , left elbow , right elbow , left wrist , right wrist , left hip , right hip , left knee , right knee , left ankle , right ankle,left elbow angle , right elbow angle , left shoulder angle , right shoulder angle , left hip angle , right hip angle , left knee angle , right knee angle
0.0,0.0,[ 0.27054 0.32959] , [ 0.27079 0.32787] , [ 0.26698 0.32339] , [ 0 0] , [ 0.25605 0.33095] , [ 0.27429 0.39124] , [ 0.24764 0.34531] , [ 0.29295 0.40439] , [ 0.25213 0.2805] , [ 0.31294 0.41499] , [ 0.26839 0.21751] , [ 0.25684 0.49569] , [ 0.23976 0.47824] , [ 0.26361 0.59153] , [ 0.25314 0.57706] , [ 0.26301 0.68071] , [ 0.25716 0.68032],
,,,172.7757568359375
,,,169.49624633789062
,,,64.31809997558594
,,,179.4266357421875
,,,166.47421264648438
,,,168.8917999267578
,,,175.57078552246094
,,,174.5126953125

Desired Output


frame_id,person_id,nose , left eye , right eye , left ear , right ear , left shoulder , right shoulder , left elbow , right elbow , left wrist , right wrist , left hip , right hip , left knee , right knee , left ankle , right ankle,left elbow angle , right elbow angle , left shoulder angle , right shoulder angle , left hip angle , right hip angle , left knee angle , right knee angle
0.0,0.0,[ 0.27054 0.32959] , [ 0.27079 0.32787] , [ 0.26698 0.32339] , [ 0 0] , [ 0.25605 0.33095] , [ 0.27429 0.39124] , [ 0.24764 0.34531] , [ 0.29295 0.40439] , [ 0.25213 0.2805] , [ 0.31294 0.41499] , [ 0.26839 0.21751] , [ 0.25684 0.49569] , [ 0.23976 0.47824] , [ 0.26361 0.59153] , [ 0.25314 0.57706] , [ 0.26301 0.68071] , [ 0.25716 0.68032], 172.7757568359375, 169.49624633789062, 64.31809997558594, 179.4266357421875, 166.47421264648438, 168.8917999267578, 175.57078552246094, 174.5126953125

Problem:


for ja in ja_list:
angle = calculate_angle(xy[ja[0]],xy[ja[1]],xy[ja[2]])
str_angle = angle

data.append({angles})


I think the problem is the data.append is being looped.

I need a way to append all 8 angle values once

Solution:


for kp_id, (ja, xy, kp_conf) in enumerate(zip(ja_list, xy, conf)):
xy_str = ', '.join(map(str, xy)) # Convert the array to a comma-separated string

angles = [str(calculate_angle(xy[ja[0]], xy[ja[1]], xy[ja[2]])) for ja in ja_list]
str_angles = ', '.join(map(str, angles)).replace("'", "")

data.append({"frame_id": frame_id, "person_id": person_id, "xy": xy_str, "angles": str_angles})


Desired Output achieved!

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