Matplotlib-无法分配位图

Question

基本上，我只是运行一个for循环，该循环绘制并将一堆图形保存为PNG，当我总共想保存25个图形时，出现了“分配位图失败”错误，但是我做了确保清除每个轴之间的轴，图形和图形窗口，那有什么用？

这是我的代码，以防万一：

def update_trade_graphs(instruments):
    print('chokepoint 13')
    for i in range(0, len(instruments)):
        if instruments[i].linked_trade is False:
            continue

        # Update variables
        bid = instruments[i].orderbook['bids'][0][0] if len(instruments[i].orderbook['bids']) > 0 else None
        ask = instruments[i].orderbook['asks'][0][0] if len(instruments[i].orderbook['asks']) > 0 else None

        trades[instruments[i].linked_trade].time_series.append(date2num(current_time_mark))
        trades[instruments[i].linked_trade].bid_prices.append(bid)
        trades[instruments[i].linked_trade].ask_prices.append(ask)

        for timespan in timespans_all:
            if timespan in trades[instruments[i].linked_trade].buy_targets:
                pass
            else:
                trades[instruments[i].linked_trade].buy_targets[timespan] = []

            trades[instruments[i].linked_trade].buy_targets[timespan].append(instruments[i].minmax[timespan][0])

            if timespan in trades[instruments[i].linked_trade].sell_targets:
                pass
            else:
                trades[instruments[i].linked_trade].sell_targets[timespan] = []

            trades[instruments[i].linked_trade].sell_targets[timespan].append(instruments[i].minmax[timespan][1])

        # Plot graph
        fig = plt.figure()
        ax1 = plt.subplot2grid((1, 1), (0, 0))

        for timespan in timespans_all:
            ax1.plot_date(trades[instruments[i].linked_trade].time_series,
                          trades[instruments[i].linked_trade].buy_targets[timespan], '-', label='Buy Target', color='c')
            ax1.plot_date(trades[instruments[i].linked_trade].time_series,
                          trades[instruments[i].linked_trade].sell_targets[timespan], '-', label='Sell Target',
                          color='m')

        ax1.plot_date(trades[instruments[i].linked_trade].time_series, trades[instruments[i].linked_trade].bid_prices,
                      '-', label='Bid', color='r')
        ax1.plot_date(trades[instruments[i].linked_trade].time_series, trades[instruments[i].linked_trade].ask_prices,
                      '-', label='Ask', color='b')

        ax1.axhline(trades[instruments[i].linked_trade].entry_price, linestyle=':', color='c')
        if trades[instruments[i].linked_trade].exit_price > 0:
            ax1.axhline(trades[instruments[i].linked_trade].exit_price, linestyle=':', color='m')

        for label in ax1.xaxis.get_ticklabels():
            label.set_rotation(90)
        ax1.grid(True)

        plt.xlabel('Date')
        plt.ylabel('Price')
        plt.title(trades[instruments[i].linked_trade].symbol)

        plt.subplots_adjust(left=0.09, bottom=0.23, right=0.94, top=0.95, wspace=0.2, hspace=0)

        plt.savefig('trade_{0}.png'.format(instruments[i].linked_trade))
        plt.close(fig)
        plt.clf()
        plt.cla()