参考：https://github.com/xuhuasheng/mmdetection_plot_pr_curve

适用于COCO数据集

import os
import mmcv
import numpy as np
import matplotlib.pyplot as plt

from pycocotools.coco import COCO
from pycocotools.cocoeval import COCOeval

from mmcv import Config
from mmdet.datasets import build_dataset

def getPRArray(config_file, result_file, metric="bbox"):
    """plot precison-recall curve based on testing results of pkl file.

        Args:
            config_file (list[list | tuple]): config file path.
            result_file (str): pkl file of testing results path.
            metric (str): Metrics to be evaluated. Options are
                'bbox', 'segm'.
    """

    cfg = Config.fromfile(config_file)
    # turn on test mode of dataset
    if isinstance(cfg.data.test, dict):
        cfg.data.test.test_mode = True
    elif isinstance(cfg.data.test, list):
        for ds_cfg in cfg.data.test:
            ds_cfg.test_mode = True

    # build dataset
    dataset = build_dataset(cfg.data.test)
    # load result file in pkl format
    pkl_results = mmcv.load(result_file)
    # convert pkl file (list[list | tuple | ndarray]) to json
    json_results, _ = dataset.format_results(pkl_results)
    # initialize COCO instance
    coco = COCO(annotation_file=cfg.data.test.ann_file)
    coco_gt = coco
    coco_dt = coco_gt.loadRes(json_results[metric])
    # initialize COCOeval instance
    coco_eval = COCOeval(coco_gt, coco_dt, metric)
    coco_eval.evaluate()
    coco_eval.accumulate()
    coco_eval.summarize()
    # extract eval data
    precisions = coco_eval.eval["precision"]
    '''
    precisions[T, R, K, A, M]
    T: iou thresholds [0.5 : 0.05 : 0.95], idx from 0 to 9
    R: recall thresholds [0 : 0.01 : 1], idx from 0 to 100
    K: category, idx from 0 to ...
    A: area range, (all, small, medium, large), idx from 0 to 3
    M: max dets, (1, 10, 100), idx from 0 to 2
    '''

    return precisions

'''
out为输出的图片名字
'''
def PR(config, result, out):
    precisions = getPRArray(config, result)

    pr_array1 = precisions[0, :, 0, 0, 2]   # IOU = 0.5
    pr_array2 = precisions[1, :, 0, 0, 2]   # IOU = 0.55
    pr_array3 = precisions[2, :, 0, 0, 2]   # IOU = 0.6
    pr_array4 = precisions[3, :, 0, 0, 2]   # IOU = 0.65
    pr_array5 = precisions[4, :, 0, 0, 2]   # IOU = 0.7
    pr_array6 = precisions[5, :, 0, 0, 2]   # IOU = 0.75
    pr_array7 = precisions[6, :, 0, 0, 2]   # IOU = 0.8
    pr_array8 = precisions[7, :, 0, 0, 2]   # IOU = 0.85
    pr_array9 = precisions[8, :, 0, 0, 2]   # IOU = 0.9
    pr_array10 = precisions[9, :, 0, 0, 2]  # IOU = 0.95

    x = np.arange(0.0, 1.01, 0.01)
    for i in range(1, 6):
        pr_array1 += precisions[0, :, i, 0, 2]
        pr_array2 += precisions[1, :, i, 0, 2]
        pr_array3 += precisions[2, :, i, 0, 2]
        pr_array4 += precisions[3, :, i, 0, 2]
        pr_array5 += precisions[4, :, i, 0, 2]
        pr_array6 += precisions[5, :, i, 0, 2]
        pr_array7 += precisions[6, :, i, 0, 2]
        pr_array8 += precisions[7, :, i, 0, 2]
        pr_array9 += precisions[8, :, i, 0, 2]
        pr_array10 += precisions[9, :, i, 0, 2]

    # plot PR curve
    plt.plot(x, pr_array1/6, label="iou=0.5")
    plt.plot(x, pr_array2/6, label="iou=0.55")
    plt.plot(x, pr_array3/6, label="iou=0.6")
    plt.plot(x, pr_array4/6, label="iou=0.65")
    plt.plot(x, pr_array5/6, label="iou=0.7")
    plt.plot(x, pr_array6/6, label="iou=0.75")
    plt.plot(x, pr_array7/6, label="iou=0.8")
    plt.plot(x, pr_array8/6, label="iou=0.85")
    plt.plot(x, pr_array9/6, label="iou=0.9")
    plt.plot(x, pr_array10/6, label="iou=0.95")

    plt.xlabel("recall")
    plt.ylabel("precison")
    plt.xlim(0, 1.0)
    plt.ylim(0, 1.01)
    plt.grid(True)
    plt.legend(loc=2, bbox_to_anchor=(1.05,1.0),borderaxespad = 0.)
    plt.savefig(out, bbox_inches="tight")
    plt.close()