我有4个excel文件分别保存着科大讯飞、三六零、同花顺和昆仑万维这四只股票的数据，使用matlab内置的candle函数，绘制出2023年1月31日以来，科大讯飞、三六零、同花顺和昆仑万维这四只股票的蜡烛图，并将这四张蜡烛图绘制在同一张图中。

首先需要将这四个excel文件导入到MATLAB中，可以使用`xlsread`函数。假设这四个文件分别为`kdxfl.xlsx`、`360.xlsx`、`ths.xlsx`、`klww.xlsx`，并且都有四列数据分别为日期、开盘价、最高价和最低价。代码如下：

[kdxfl_date, kdxfl_open, kdxfl_high, kdxfl_low] = xlsread('kdxfl.xlsx');
[360_date, 360_open, 360_high, 360_low] = xlsread('360.xlsx');
[ths_date, ths_open, ths_high, ths_low] = xlsread('ths.xlsx');
[klww_date, klww_open, klww_high, klww_low] = xlsread('klww.xlsx');

接下来，需要找到2023年1月31日在数据中的位置。假设日期数据是以序列号的形式保存的，可以使用`datenum`函数将日期转换为序列号。代码如下：

target_date = datenum('2023-01-31');
kdxfl_target_idx = find(kdxfl_date >= target_date, 1);
360_target_idx = find(360_date >= target_date, 1);
ths_target_idx = find(ths_date >= target_date, 1);
klww_target_idx = find(klww_date >= target_date, 1);

现在，我们已经找到了2023年1月31日在数据中的位置。接下来，可以使用`candle`函数绘制蜡烛图。代码如下：

figure;
subplot(2,2,1);
candle(kdxfl_open(kdxfl_target_idx:end), kdxfl_high(kdxfl_target_idx:end), kdxfl_low(kdxfl_target_idx:end));
title('科大讯飞');
subplot(2,2,2);
candle(360_open(360_target_idx:end), 360_high(360_target_idx:end), 360_low(360_target_idx:end));
title('三六零');
subplot(2,2,3);
candle(ths_open(ths_target_idx:end), ths_high(ths_target_idx:end), ths_low(ths_target_idx:end));
title('同花顺');
subplot(2,2,4);
candle(klww_open(klww_target_idx:end), klww_high(klww_target_idx:end), klww_low(klww_target_idx:end));
title('昆仑万维');

最后，使用`hold on`命令将这四张蜡烛图绘制在同一张图中。代码如下：

hold on;
candle(kdxfl_open(kdxfl_target_idx:end), kdxfl_high(kdxfl_target_idx:end), kdxfl_low(kdxfl_target_idx:end));
candle(360_open(360_target_idx:end), 360_high(360_target_idx:end), 360_low(360_target_idx:end));
candle(ths_open(ths_target_idx:end), ths_high(ths_target_idx:end), ths_low(ths_target_idx:end));
candle(klww_open(klww_target_idx:end), klww_high(klww_target_idx:end), klww_low(klww_target_idx:end));
title('四只股票蜡烛图');
legend('科大讯飞', '三六零', '同花顺', '昆仑万维');

这样就可以在同一张图中绘制出四只股票的蜡烛图了。完整代码如下：

[kdxfl_date, kdxfl_open, kdxfl_high, kdxfl_low] = xlsread('kdxfl.xlsx');
[360_date, 360_open, 360_high, 360_low] = xlsread('360.xlsx');
[ths_date, ths_open, ths_high, ths_low] = xlsread('ths.xlsx');
[klww_date, klww_open, klww_high, klww_low] = xlsread('klww.xlsx');

target_date = datenum('2023-01-31');
kdxfl_target_idx = find(kdxfl_date >= target_date, 1);
360_target_idx = find(360_date >= target_date, 1);
ths_target_idx = find(ths_date >= target_date, 1);
klww_target_idx = find(klww_date >= target_date, 1);

figure;
subplot(2,2,1);
candle(kdxfl_open(kdxfl_target_idx:end), kdxfl_high(kdxfl_target_idx:end), kdxfl_low(kdxfl_target_idx:end));
title('科大讯飞');
subplot(2,2,2);
candle(360_open(360_target_idx:end), 360_high(360_target_idx:end), 360_low(360_target_idx:end));
title('三六零');
subplot(2,2,3);
candle(ths_open(ths_target_idx:end), ths_high(ths_target_idx:end), ths_low(ths_target_idx:end));
title('同花顺');
subplot(2,2,4);
candle(klww_open(klww_target_idx:end), klww_high(klww_target_idx:end), klww_low(klww_target_idx:end));
title('昆仑万维');

hold on;
candle(kdxfl_open(kdxfl_target_idx:end), kdxfl_high(kdxfl_target_idx:end), kdxfl_low(kdxfl_target_idx:end));
candle(360_open(360_target_idx:end), 360_high(360_target_idx:end), 360_low(360_target_idx:end));
candle(ths_open(ths_target_idx:end), ths_high(ths_target_idx:end), ths_low(ths_target_idx:end));
candle(klww_open(klww_target_idx:end), klww_high(klww_target_idx:end), klww_low(klww_target_idx:end));
title('四只股票蜡烛图');
legend('科大讯飞', '三六零', '同花顺', '昆仑万维');