display(data_frame[data_frame.数学 > "95"])怎么数学成绩大于100的显示不出来
时间: 2024-09-21 12:02:54 浏览: 12
`display(data_frame[data_frame.数学 > "95"])` 这段代码是在Python的数据分析库Pandas中使用的,它试图筛选出数据框(data_frame)中数学成绩大于95分的所有行。但是,这里可能会出现问题,因为通常在Pandas中,数值型列如"数学"应该是数字而不是字符串。如果"数学"列存储的是实际的数字,那么比较条件 `maths > "95"` 将不会生效,因为它会尝试将数字与字符串比较。
如果你的数据集中数学成绩是以字符串形式表示,例如 "A"、"B" 等等级对应的分数(这种情况下超过100分可能表示为 "A+" 或者类似),那么这个比较会失败,因为95以上的数字级不会匹配上"A+"这样的字符串。
正确的做法应该是先将成绩转换为数值类型再进行比较,例如:
```python
# 假设 '数学' 列是字符串类型,需要转换成数字
data_frame['数学'] = pd.to_numeric(data_frame['数学'])
# 然后再筛选
filtered_data = data_frame[data_frame['数学'] > 95]
display(filtered_data)
```
如果数据本来就是数字格式,但是没有显示出来任何结果,可能是由于数据框为空或者没有任何记录的数学成绩超过95分。检查一下`data_frame['数学'].max()`是否小于等于95即可确认。
相关问题
import threading import cv2 import tkinter as tk from tkinter import * from PIL import Image, ImageTk#图像控件 from Background.Thread_Demo import Thread_data from Data_demo import data_demo class Two_Layout(): def __init__(self, top): self.top = top self.canvas2 = Canvas(self.top, bg='LightSkyBlue', width=1100, height=610, highlightthickness=2, highlightbackground='Black') self.canvas2.place(x=0, y=28) data_demo.display_id = self.canvas2 Thread_data(self.Thread_()) def Thread_(self): self.cap = cv2.VideoCapture(0) t = threading.Thread(target=self.windows_display()) t.start() def windows_display(self): ref, frame = self.cap.read() data_demo.display_id.delete('all') label = tk.Label(data_demo.display_id, text='未接入摄像头!', font=("黑体", 25), width=15, height=1) if ref is False: label.place(x=400, y=300, anchor='nw') self.cap = cv2.VideoCapture(0) else: for widget in data_demo.display_id.winfo_children(): widget.destroy() image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB) image1 = Image.fromarray(image) image2 = image1.resize((1100, 645), Image.ANTIALIAS) self.photo = ImageTk.PhotoImage(image=image2) data_demo.display_id.create_image(0, 0, image=self.photo, anchor=tk.NW) data_demo.display_id.after(15, self.windows_display)为什么还是与filedialog.askopenfilename()起了冲突
你的代码中没有引入 `filedialog`,所以很难确定具体原因。但是,在你的代码中,没有直接调用 `filedialog.askopenfilename()`,所以很可能是其他部分的代码和 `filedialog` 产生了冲突。请检查你的代码并确定是否有其他部分调用了 `filedialog.askopenfilename()`。另外,检查你的代码是否正确导入了 `filedialog`。如果你仍然无法解决问题,请提供更多的细节和代码,以便我能够更好地帮助你。
ffmpeg音频解码av_frame_alloc
av_frame_alloc函数用于为AVFrame结构体分配内存空间,AVFrame结构体用于存储解码后的音视频数据。在音频解码中,可以通过调用该函数为AVFrame结构体分配内存空间,然后将解码后的音频数据存储到该结构体中,最后再进行后续的处理操作。
具体使用方法如下:
```c
AVFrame *frame = av_frame_alloc();
if (!frame) {
// 内存分配失败处理
}
```
其中,AVFrame结构体的定义如下:
```c
typedef struct AVFrame {
/**
* pointers to the data planes/channels.
* This might be different from the first allocated byte
*/
uint8_t *data[AV_NUM_DATA_POINTERS];
/**
* For video, size in bytes of each picture line.
* For audio, size in bytes of each plane.
*/
int linesize[AV_NUM_DATA_POINTERS];
/**
* pointers to the start of each picture line.
* This is used for both video and audio.
*/
uint8_t **extended_data;
/**
* width and height of the video frame
*/
int width, height;
/**
* number of audio samples (per channel) described by this frame
*/
int nb_samples;
/**
* format of the frame, -1 if unknown or unset
* Values correspond to enum AVPixelFormat for video frames,
* enum AVSampleFormat for audio)
*/
int format;
/**
* 1 -> keyframe, 0-> not
*/
int key_frame;
/**
* Picture type of the frame.
*/
enum AVPictureType pict_type;
/**
* Quality (between 1 (good) and FF_LAMBDA_MAX (bad)).
*/
int quality;
/**
* for AV_PIX_FMT_*_BE formats, linesize alignment
*/
int64_t best_effort_timestamp;
/**
* PTS copied from the AVPacket that was decoded to produce this frame.
*/
int64_t pkt_pts;
/**
* DTS copied from the AVPacket that triggered returning this frame.
*/
int64_t pkt_dts;
/**
* duration of the corresponding packet, expressed in
* AVStream->time_base units, 0 if unknown.
*/
int64_t pkt_duration;
uint64_t metadata;
int decode_error_flags;
/**
* number of audio channels
*/
int channels;
/**
* size of the corresponding packet containing the compressed
* frame. It is set to a negative value if unknown.
*/
int pkt_size;
/**
* data type
*/
enum AVSampleFormat sample_fmt;
/**
* presentation timestamp in timebase units
* (time when frame should be shown to user)
* If AV_NOPTS_VALUE then frame_rate = 1/time_base will be assumed.
*/
int64_t pts;
/**
* reordered PTS from the last AVPacket that has been input into the decoder
*/
int64_t best_effort_timestamp;
/**
* sample aspect ratio (0 if unknown)
* - encoding: Set by user.
* - decoding: Set by libavcodec.
*/
AVRational sample_aspect_ratio;
/**
* motion vector table, used for MPEG1/2/4 and H.263 decoding
*/
struct AVPanScan *pan_scan;
/**
* macroblock decision mode
*/
int coded_picture_number;
int display_picture_number;
/**
* quality (between 1 (good) and FF_LAMBDA_MAX (bad))
*/
int quality;
/**
* buffer age (1->was last buffer and dint change, 2->..., ...)
*/
int age;
/**
* is this picture used as reference
*/
int reference;
/**
* QP table
*/
int8_t *qp_table_buf;
/**
* QP store stride
*/
int qp_table_linesize;
/**
* QP values for each macroblock
*/
int8_t *qp_table;
/**
* For hwaccel-format frames, this should be a reference to the
* AVHWFramesContext describing the frame.
* For normal-format frames, this should be NULL.
*/
AVBufferRef *hw_frames_ctx;
} AVFrame;
```
需要注意的是,AVFrame结构体中的成员变量很多,具体使用哪些成员变量取决于具体的应用场景和需求。