Matlab图形直方图，指示文件中每个字符的总和 [英] matlab plot histogram indicating sum of each character inside a file

问题描述

我有400个文件，每个文件包含大约500000个字符，而这500000个字符仅由大约20个字母组成.我想制作一个直方图，指示使用的最多10个字母(x轴)和每个字母的使用次数(y轴).我该怎么做.

I have 400 files, each one contains about 500000 character, and those 500000 characters consists only from about 20 letters. I want to make a histogram indicating the most 10 letters used (x-axis) and number of times each letter is used (y-axis). how can i make it.

推荐答案

由于具有uchar数组，因此您知道元素将始终在0:255范围内.在看到TamásSzabó的答案在这里后，我意识到文本文件中的空字符极少出现，因此我将忽略它并使用范围1:255.如果希望使用空字符，则必须调整范围.

Since you have an array of uchar, you know that your elements will always be in the range 0:255. After seeing Tamás Szabó's answer here I realized that the null character is exceedingly unlikely in a text file, so I will just ignore it and use the range 1:255. If you expect to have null characters, you'll have to adjust the range.

为了找到10个最常用的字母，我们将首先计算直方图计数，然后按降序对它们进行排序并取前10个:

In order to find the 10 most frequently-used letters, we'll first calculate the histogram counts, then sort them in descending order and take the first 10:

counts = histc(uint8(part), [1:255]);
[topCounts, topIndices] = sort(counts, 'descend');

现在，我们需要重新排列计数和索引，以按字母顺序将字母放回原位:

Now we need to rearrange the counts and indices to put the letters back in alphabetical order:

[sortedChars, shortIndices] = sort(topIndices(1:10));
sortedCounts = topCounts(shortIndices);

现在我们可以使用bar绘制直方图了:

Now we can plot the histogram using bar:

bar(sortedCounts);

(如果希望图形中的条像正常的hist图中的条一样触摸，则可以添加'hist'选项.)

(You can add the 'hist' option if you want the bars in the graph touching like they do in the normal hist plot.)

要将水平图例从数字值更改为字符，请使用sortedChars作为'XtickLabel':

To change the horizontal legend from numeric values to characters, use sortedChars as the 'XtickLabel':

labelChars = cellstr(sortedChars.').';
set(gca, 'XtickLabel', labelChars);

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