Cannot read properties of undefined (reading 'histogram')
时间: 2023-11-20 18:58:23 浏览: 13
这个错误通常是由于尝试访问未定义的对象属性而引起的。可能的原因是该对象未被正确初始化或已被删除。要解决此问题,您可以检查代码中的对象初始化和删除操作,并确保它们正确无误。您还可以使用JavaScript的可选链操作符(?.)来避免访问未定义的属性。例如:
```javascript
const histogram = data?.histogram;
```
这将在data对象已定义时返回histogram属性的值,否则返回undefined,而不会引发TypeError异常。
相关问题
non weighted histogram of read lengths
Sure, I can help you with that.
A non-weighted histogram of read lengths is a graphical representation of the distribution of read lengths in a set of sequencing data. In this type of histogram, each read length is represented by a single count, regardless of the number of times that length occurs in the dataset.
To create a non-weighted histogram of read lengths, you can follow these steps:
1. Collect the read length data from your sequencing dataset.
2. Determine the range of read lengths in your dataset.
3. Divide the range of read lengths into a series of bins, each representing a range of read lengths.
4. Count the number of reads in each bin.
5. Plot the bin counts on the y-axis and the bin ranges on the x-axis to create a histogram.
Here's an example code snippet in Python to create a non-weighted histogram of read lengths using the Matplotlib library:
```
import matplotlib.pyplot as plt
# Example read length data
read_lengths = [100, 200, 300, 400, 500, 200, 300, 300, 100, 100, 200, 500, 500]
# Define the bin ranges
bins = range(0, 600, 100)
# Count the number of reads in each bin
bin_counts, _, _ = plt.hist(read_lengths, bins=bins, color='blue')
# Plot the histogram
plt.xlabel('Read length')
plt.ylabel('Count')
plt.title('Non-weighted histogram of read lengths')
plt.show()
```
This code will create a histogram with five bins representing read lengths from 0-100, 100-200, 200-300, 300-400, and 400-500. The bin counts will be [4, 4, 3, 1, 2], respectively, and the resulting histogram will show the distribution of read lengths in the dataset.
please show the code of creating a histogram in ROOT
### 回答1:
在ROOT中创建直方图的代码如下:
```
#include <TH1D.h>
#include <TCanvas.h>
#include <TRandom.h>
void histogram() {
TH1D *h = new TH1D("h", "Example Histogram", 100, -4, 4);
TRandom r;
for (int i = 0; i < 10000; i++) {
h->Fill(r.Gaus(0, 1));
}
TCanvas *c = new TCanvas("c", "Example Histogram", 800, 600);
h->Draw();
c->SaveAs("histogram.pdf");
}
```
这段代码创建了一个名为"h"的1维直方图,包含了100个柱子,数据范围在-4到4之间。然后使用TRandom生成了10000个高斯分布的随机数,并将它们填入直方图。最后,创建了一个TCanvas,将直方图绘制到画布上,并将画布保存为PDF文件。
### 回答2:
在ROOT中创建直方图的代码可以通过以下步骤实现:
首先,我们需要在程序中导入必要的文件以使用ROOT的相关功能。代码如下所示:
```cpp
#include <TH1.h>
#include <TCanvas.h>
#include <TROOT.h>
#include <TRandom.h>
```
接下来,我们需要创建一个TCanvas对象,它将用于显示直方图。代码如下所示:
```cpp
TCanvas *c1 = new TCanvas("c1", "Histogram", 800, 600);
c1->SetFillColor(kWhite);
```
然后,我们可以定义并填充直方图。在本例中,我们将使用随机数生成器来填充一个100个数的直方图。代码如下所示:
```cpp
TH1F *histogram = new TH1F("histogram", "Example Histogram", 100, 0, 100);
TRandom random;
for (int i = 0; i < 100; i++) {
double value = random.Gaus(50, 10); // 使用高斯分布生成随机数
histogram->Fill(value);
}
```
接下来,我们可以设置直方图的各种属性,例如标题、坐标轴名称和线条颜色等。代码如下所示:
```cpp
histogram->SetTitle("Example Histogram");
histogram->GetXaxis()->SetTitle("x");
histogram->GetYaxis()->SetTitle("Counts");
histogram->SetLineColor(kBlue);
```
最后,我们可以使用c1对象来在屏幕上绘制直方图。代码如下所示:
```cpp
histogram->Draw();
c1->Update();
```
以上就是在ROOT中创建直方图的代码示例。你可以根据需要进一步修改和扩展此代码,以满足你的具体需求。
### 回答3:
在ROOT中创建直方图的代码如下:
```cpp
#include <TH1F.h>
#include <TCanvas.h>
void createHistogram() {
// 创建一个直方图对象
TH1F *histogram = new TH1F("histogram", "Histogram", 100, 0, 10);
// 向直方图中添加数据点
histogram->Fill(2);
histogram->Fill(4);
histogram->Fill(5);
histogram->Fill(7);
// 创建一个画布对象
TCanvas *canvas = new TCanvas("canvas", "Histogram Canvas", 800, 600);
// 将直方图绘制在画布上
histogram->Draw();
// 显示画布
canvas->Draw();
}
```
首先,我们使用`TH1F`类创建了一个名为`histogram`的直方图对象,它有100个bin,范围从0到10。然后,通过`Fill()`函数向直方图添加了数据点,这里添加了4个数据点:2、4、5和7。
接下来,我们创建了一个名为`canvas`的画布对象,它的尺寸为800x600像素。我们使用`Draw()`函数将直方图绘制在画布上,然后使用`Draw()`函数将画布显示出来。
这段代码实现了在ROOT中创建直方图的基本操作,你可以根据实际需求调整直方图的参数和数据点。
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