现在有一组数据： 1224 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1225 (_sex male) (_age child) (_race white) (_face smiling) (_prop '()) 1226 (_sex male) (_age child) (_race white) (_face smiling) (_prop '()) 1227 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1228 (_missing descriptor) 1229 (_sex male) (_age adult) (_race white) (_face serious) (_prop '()) 1230 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1231 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1232 (_missing descriptor) 1233 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1234 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1235 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1236 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1237 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1238 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1239 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1240 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1241 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1242 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1243 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1244 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1245 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1246 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1247 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1248 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1249 (_sex male) (_age child) (_race white) (_face funny) (_prop '()) 1250 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1251 (_sex male) (_age child) (_race white) (_face serious) (_prop '()) 1252 (_sex female) (_age child) (_race white) (_face smiling) (_prop '())，根据sex，分为male一组和female一组

可以使用MATLAB中的逻辑索引来实现将数据根据'sex'分为'male'一组和'female'一组。具体步骤如下：

% 读取数据
data = readtable('filename.txt', 'Delimiter', {' ', '(', ')'}, 'ReadVariableNames', false);

% 根据'sex'分为'male'一组和'female'一组
is_male = strcmp(data.Var2, 'male'); % 判断是否为'male'
male_data = data(is_male, :); % 将'male'数据筛选出来
female_data = data(~is_male, :); % 将'female'数据筛选出来

上述代码中，首先使用之前提到的方法读取数据。然后，使用逻辑索引`strcmp(data.Var2, 'male')`来判断每个数据是否为'male'。将结果保存到`is_male`中。最后，使用逻辑索引`is_male`和`~is_male`来将数据分为'male'一组和'female'一组，分别保存到`male_data`和`female_data`中。